# Qwen3.5 397B vs Seed 2.1 Pro

> Side-by-side benchmark comparison for Qwen3.5 397B and Seed 2.1 Pro across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/qwen3-5-397b-vs-seed-2-1-pro
- Last updated: September 10, 2026

- Shared sourced benchmarks: 4
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Pick Qwen3.5 397B if you want the stronger benchmark profile. Seed 2.1 Pro only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Qwen3.5 397B leads overall 54.7 to 0.
- The biggest single benchmark swing is CharXiv in Multimodal & Grounded, with scores of 80.8% and 85.4%.
- Seed 2.1 Pro is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- Seed 2.1 Pro also has the larger context window at 256K.

## Model Snapshot

| Property | Qwen3.5 397B | Seed 2.1 Pro |
|----------|----------|----------|
| Creator | Alibaba | ByteDance |
| Type | Open Weight | Proprietary |
| Reasoning | Non-Reasoning | Reasoning |
| Context | 128K | 256K |
| Overall Score | 54.7 | null |
| Benchmarks Covered | 38 | 11 |
| Pricing (input/output) | $0.60 / $3.60 | Pricing unavailable / Pricing unavailable |

## Category Breakdown

### Agentic

- Winner: Coming soon
- Qwen3.5 397B public-lane score: 46.8 (Estimated · #71/152)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Qwen3.5 397B | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.0 | 52.5% | Coming soon | Coming soon |
| BrowseComp | 62% | Coming soon | Coming soon |
| Claw-Eval | 56.8% | Coming soon | Coming soon |
| QwenClawBench | 51.8% | Coming soon | Coming soon |
| τ³-bench results | 68.4% | Coming soon | Coming soon |
| VITA-Bench | 43.7% | Coming soon | Coming soon |
| DeepPlanning | 37.6% | Coming soon | Coming soon |
| Toolathlon | 36.3% | Coming soon | Coming soon |
| MCP Atlas | 46.1% | Coming soon | Coming soon |
| MCP-Tasks | 74.2% | Coming soon | Coming soon |
| WideResearch | 74.0% | Coming soon | Coming soon |
| Gert Labs | 46.76% | Coming soon | Coming soon |
| ResearchClawBench | 14.2% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 71.0% | Coming soon |

### Coding

- Winner: Coming soon
- Qwen3.5 397B public-lane score: 50.2 (Estimated · #59/151)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Qwen3.5 397B | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 76.2% | Coming soon | Coming soon |
| LiveCodeBench v6 | 83.6% | Coming soon | Coming soon |
| SWE-bench Pro | 50.9% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 71.0% | Coming soon |
| NL2Repo | Coming soon | 47% | Coming soon |

### Multimodal & Grounded

- Winner: Coming soon
- Qwen3.5 397B public-lane score: 63 (#27/48)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Qwen3.5 397B | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | 79% | 81.6% | Seed 2.1 Pro |
| MathVision | 88.6% | 92.6% | Seed 2.1 Pro |
| CharXiv | 80.8% | 85.4% | Seed 2.1 Pro |
| VideoMMMU | 84.7% | Coming soon | Coming soon |
| ScreenSpot Pro | 65.6% | Coming soon | Coming soon |
| V* | 95.8% | Coming soon | Coming soon |
| ZeroBench | Coming soon | 18.0% | Coming soon |
| BabyVision | Coming soon | 73.7% | Coming soon |
| ERQA | Coming soon | 72.0% | Coming soon |
| Video-MME | Coming soon | 89.2% | Coming soon |

### Reasoning

- Winner: Coming soon
- Qwen3.5 397B public-lane score: 59.8 (Unranked · 2 rankable rows)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Qwen3.5 397B | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| LongBench v2 | 63.2% | Coming soon | Coming soon |
| AI-Needle | 68.7% | Coming soon | Coming soon |

### Knowledge

- Winner: Coming soon
- Qwen3.5 397B public-lane score: 50.2 (Estimated · #77/183)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Qwen3.5 397B | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| GPQA | 88.4% | Coming soon | Coming soon |
| SuperGPQA | 70.4% | 70.8% | Seed 2.1 Pro |
| MMLU-Pro | 87.8% | Coming soon | Coming soon |
| MMLU-Redux | 94.9% | Coming soon | Coming soon |
| C-Eval | 93% | Coming soon | Coming soon |
| HLE | 28.7% | Coming soon | Coming soon |

### Instruction Following

- Winner: Coming soon
- Qwen3.5 397B public-lane score: 0 (#123/123)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Qwen3.5 397B | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| IFEval | 92.6% | Coming soon | Coming soon |

### Multilingual

- Winner: Coming soon
- Qwen3.5 397B public-lane score: 69.7 (#5/12)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Qwen3.5 397B | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| MMLU-ProX | 84.7% | Coming soon | Coming soon |
| NOVA-63 | 59.1% | Coming soon | Coming soon |

### Mathematics

- Winner: Coming soon
- Qwen3.5 397B public-lane score: 74.2 (Unranked · 5 rankable rows)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Qwen3.5 397B | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| AIME26 | 93.3% | Coming soon | Coming soon |
| HMMT Feb 2025 | 94.8% | Coming soon | Coming soon |
| HMMT Nov 2025 | 92.7% | Coming soon | Coming soon |
| HMMT Feb 2026 | 87.9% | Coming soon | Coming soon |
| MMAnswerBench | 80.9% | Coming soon | Coming soon |

## FAQ

### Which is better overall, Qwen3.5 397B or Seed 2.1 Pro?

Qwen3.5 397B is ahead overall on BenchLM right now.

### How many benchmarks does Qwen3.5 397B cover on BenchLM?

Qwen3.5 397B currently has 38 sourced benchmark scores on BenchLM.

### How many benchmarks does Seed 2.1 Pro cover on BenchLM?

Seed 2.1 Pro currently has 11 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Qwen3.5 397B vs Qwen3.5 397B (Reasoning)](/compare/qwen3-5-397b-vs-qwen3-5-397b-reasoning)
- [Seed 2.1 Pro vs Qwen3.5 397B (Reasoning)](/compare/qwen3-5-397b-reasoning-vs-seed-2-1-pro)
- [Qwen3.5 397B vs Seed 2.1 Turbo](/compare/qwen3-5-397b-vs-seed-2-1-turbo)
- [Seed 2.1 Pro vs Seed 2.1 Turbo](/compare/seed-2-1-pro-vs-seed-2-1-turbo)

## Explore More

- [Qwen3.5 397B profile](/models/qwen3-5-397b)
- [Seed 2.1 Pro profile](/models/seed-2-1-pro)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)