Under the goal of carbon neutrality, public participation in green travel is the fundamental premise of low-carbon transportation development. Based on the multiple mediation effect model, this paper explores the mechanism of social interaction on public participation in low-carbon transportation, and the hierarchical regression method is used to test the moderating effect of social network intensity and information network intensity. The results show that: (1) Both network media and social relations have a prominent positive effect on public participation, but the effect of network media is better than that of social relations. (2) Network media and social relations affect residents’ low-carbon travel behavior through three mediating variables, namely, traffic information, environmental protection knowledge and social norms. (3) The moderating effect of social network intensity on the relationship between network media and low-carbon travel behavior is prominently negative, while the moderating effect of information network intensity is significantly positive. Therefore, it is necessary to stimulate more public participation in low-carbon transport through real-time pushing of traffic information and strengthening the closeness of social relations.