In tracing two Chinese rural middle school classes for 3 years, this study found the positive impact of adopting the algorithm-based mobile short video platform Douyin on rural adolescents' intrinsic motivation. The application's broad adoption has reshaped the social processes supporting adolescent users' intrinsic motivation and spontaneous pursuit of life possibilities. In the online interaction based on algorithms, the rural adolescents discover and govern themselves during the algorithms-driven exploration and expression; they also conduct informational and emotional reciprocity with an algorithmic collectivity emerging from clustering technologies. In the offline interaction with the living community, the platform-state digital economy agenda has intervened and coordinated the local cultural attitudes towards youth development with an entrepreneurial solutionism. This study adds to the previous less empirically addressed issue of the rising algorithmic short video service and intrinsic motivation, and puts forward an ecological explanation concerning the national policy, platform business, and the user's self-consciousness.