Based on resource arrangement theory and competition and cooperation theory, a theoretical path of "small and medium-sized enterprises (SMEs) participation platform ecology-integration and utilization of digital resources-digital transformation performance" was formed, and an integration logic of SMEs' "collaboration with leading enterprises" and "collaboration with other participating enterprises" in platform participation affects digital transformation performance was constructed. Based on the survey data of 954 SMEs, the empirical test using statistical method shows that SMEs can promote the breadth and depth of their digital resource integration by cooperating with the platform leading enterprises and other participating enterprises, but the collaboration with the leading enterprises can promote the depth of integration, and the collaboration with other participating enterprises can promote the breadth of integration. The breadth of digital resource integration of SMEs has a positive U-shaped impact on digital transformation performance, and the depth of integration has an inverted U-shaped impact on transformation performance. The breadth and depth of integration can play a corresponding nonlinear intermediary effect between "inter-enterprise collaboration-digital transformation performance". It provides a theoretical reference for promoting the implementation of digital transformation in SMEs through platform-enabled collaboration with diverse entities.