With the development of online education and the popularization of mobile Internet, the scale of online education mobile application market and the scale of users are steadily expanding, and more and more people learn through online education, but when users receive online education, users have higher requirements for the quality and effect of online education.Based on flow theory, a flow model in online education environment is proposed, which includes nine flow factors: challenge, response speed, sense of control, clear goal, timely feedback, perceived ease of use, interactivity, learning intention and learning achievement. Finally, based on the flow model, the corresponding design strategy is put forward to guide the design practice.