Abstract: The large-scale integration of electric vehicles (EV) has promoted the decarbonization agenda of transportation sectors while also raising challenges for the stable, efficient operation of the power grid. In transportation-electricity coupling, multiple uncertain factors influence EV fleets' aggregate charging load. It should be investigated how to fully exploit EVs' flexibility for low-carbon optimization. Therefore, this article proposes a multi-time scale decarbonization coordination strategy for EV fleets considering transportation-electricity coupling. First, a decarbonization coordination framework is proposed. Then, a multi-time scale low-carbon coordination model for EV fleets is established. Furthermore, based on the Copula theory, the multiple uncertainties and their interaction are accurately modeled. Given typical scenarios, the problem is solved as scenario-based stochastic programming problems. Finally, the effectiveness of the proposed method is verified through numerical case studies.