Abstract: Forest carbon sequestration is one of the important ways to mitigate climate change. Forest farmers' intention to participate in forest carbon sequestration has a root effect on carbon sequestration management. In this study, social trust, the core element of social capital theory, was incorporated into TPB theory. The structural equation model was used to analyze 206 forest farmers in Heping County. The results showed that social trust had a positive driving effect on farmers' intention to participate; subjective norms directly or indirectly drove farmers' intention to participate through farmers' participation attitude; perceptual behavior control indirectly drove farmers' intention to participate through farmers' participation attitude, and there was no direct driving effect on farmers' intention to participate. The conclusions provided theoretical and practical basis for promoting forest farmers to participate in forestry carbon sequestration projects.