This study explores the carbon reduction and carbon leakage effect and their heterogeneity in different China’s carbon trading pilots. Multi-regional input–output method, and double and triple difference methods are used for calculating carbon transfer and empirical analysis of carbon leakage. The research results suggest unilateral environmental regulations can lead to positive carbon leakage to nonpilot areas through industrial transfer channels, which is evident in various accounting ranges of carbon transfer. The contribution of different pilot provinces and cities to carbon reduction and carbon leakage is heterogeneous. The above research provides reference and inspiration for China to further improve the construction of the national carbon market.