This paper analyses direct and indirect mechanisms of the promoting effect of green technology innovation of transport companies on the SSC development. Based on China’s transport sector data, we conduct an empirical study using the LL-FE model. Theoretical and empirical studies have two key findings: (1) On the direct mechanism, green technology innovations of transport companies have a positive role of promoting SSC development. When the level of green technological innovation of transportation enterprises increases by 1% totally, the level of transportation carbon emissions decreases by about 0.23%. (2) As for indirect mechanisms, green technology innovations of transport companies will promote SSC development through technology spill over, market competition and social network. This paper enriches the understanding of green technological innovation and SSC both in theoretical and empirical aspects.