Exploring the influencing factors of users' sustained contribution behavior in UGC short video communities and their mechanism of action is of positive significance to enhance the motivation of users' sustained contribution and promote the sustainable development of the short video industry. This study uses a combination of qualitative and quantitative methods to explore the main influencing factors of users' sustained contribution behavior in UGC short video communities through qualitative research based on self-determination theory, and then constructs its theoretical model and validates it through structural equation modeling. The results found that (1) the individual factors affecting users' continuous contribution behavior are mainly self-presentation and interpersonal interaction, and the environmental factors are mainly community identity; (2) self-presentation and interpersonal interaction do not directly affect users' continuous contribution behavior significantly, but indirectly act on users' continuous contribution behavior through community identity. Finally, based on the research results, corresponding suggestions are proposed to promote the development of UGC short video communities and their users' sustained contribution behaviors.