Abstract: Taking online teaching and knowledge interaction as the research object, this paper studies the game interaction between relevant subjects on online teaching platforms and establishment and stability of online teaching platform ecosystem. For this, based on the idea of platform ecosystem, this paper establishes a three-way evolutionary game model involving knowledge providers, knowledge demanders and online teaching platforms, and reveals the operating mechanism of online teaching platform ecosystem. The results show that the differences of supply income, platform income and platform extra income have a positive impact on knowledge providers and strategy choice of online teaching platforms. The difference of cost has a negative impact on the strategy choice of participants, and also affects the strategy choice of other parties. The income influence coefficients of online teaching platform ecosystem participants mutually influence the strategic choice of other parties. The online teaching platform has a positive impact on income influence coefficient of the knowledge providers as well as strategy selection of online teaching platforms, and the income influence coefficient of deep learning has a positive impact on strategy selection of all of the three parties. With an increase of online teaching platform rewards, knowledge providers and online teaching platform strategies have evolved from participation and maintenance to deep participation and active development.