Chinese AI model Kimi K3.1 Pro is closing in on Anthropic’s Claude Opus 5.5

Anthropic — moonshot AI’s new reasoning model Kimi K3.1 Pro lands at number four on the Artificial Analysis Intelligence Index, just 3 points behind the top proprietary models. Chinese AI company Moonshot AI has released Kimi K3.1 Pro, a post-trained version of its predecessor Kimi K3 with significantly more post-training compute.

The model scores 55 points on the Artificial Analysis Intelligence Index, an 11-point jump over K3 that lands it in fourth place. Only Claude Opus 5.5 (58), Claude Sonnet 5.5 (56), and Muse Wonder Full (56) rank higher, according to Artificial Analysis. If Moonshot releases the model weights as planned by November 4, 2026, K3.1 Pro would become the highest-scoring open-weights model available. That would shrink the gap between open and proprietary models from 12 to just 3 points, assuming nothing else changes by then.Ad Alongside K3.1 Pro, Moonshot is shipping a variant called K3.1 Pro Highspeed that runs two to three times faster, according to the company. Both are available now through Kimi.ai, Kimi Work, Kimi Code, and the Kimi API.Ad K3.1 Pro’s strongest improvements show up in agentic tasks. On the GDPval-AA benchmark, it reaches 1,846 Elo according to Artificial Analysis, 312 points above K3. That puts it just behind Claude Opus 5.5 (1,866) and Muse Wonder Full (1,857). On Terminal-Bench 4.0, Moonshot reports 65.7 percent, ahead of GPT-6 Astra (58.2 percent) and barely behind Claude Opus 5.5 (66.4 percent). K3 managed only 13 percent on the same test. Hallucination rates dropped sharply too. On Moonshot’s internal Kimi Hallu Bench Hard, claim-level hallucinations fell from 23.4 percent with K3 to 8.3 percent, according to the company. Moonshot says this is a stress test, not a measure of general error rates. GPT-6 Astra hits 5.5 percent on the same benchmark, so it still has an edge.Ad On internal finance benchmarks, K3.1 Pro gained 7.2 points on Financial Modeling and 11.6 points on Financial Research. For general office tasks, the model tops all tested models on OfficeQA Pro v2, according to Moonshot. Moonshot’s Kimi K3.1 Pro benchmark table.