OpenR1-Math-220k is a large-scale mathematical reasoning dataset released by the Open R1 team in 2025 to fill the gap in DeepSeek R1 synthetic data. The dataset contains 220,000 high-quality mathematical problems and their reasoning traces, which are derived from 800,000 reasoning traces generated by DeepSeek R1.

The dataset is divided into two parts:

• default (94k issues): This part of the data performs best after supervised fine-tuning (SFT).
• extended (131k questions): This part of the data contains additional NuminaMath 1.5 data sources, such as cn_k12, which provides more inference formulas.