MeanFlow models introduce the concept of average velocity to fundamentally reformulate one-step generative modeling. Unlike Flow Matching, which focuses on instantaneous velocity, MeanFlow directly models the displacement over a time interval. This approach allows for highly efficient one-step or few-step generation using a single network evaluation. MeanFlow is built on a principled mathematical identity between average and instantaneous velocities, guiding network training without requiring pre-training, distillation, or curriculum learning. It achieves state-of-the-art performance for one-step generation, significantly narrowing the gap with multi-step models.