Conversation Voltage Reduction (CVR) is a breakthrough technology designed to reduce energy consumption by reducing voltage within a power distribution system. This innovative approach has been successfully implemented in various distribution networks, both nationally and internationally. In view of the urgent need to achieve the “dual carbon” goals, especially in the field of railway, this paper presents the application of CVR technology in traction power supply system (TPSS). The goal is to reduce the voltage of traction network to achieve active energy saving of traction power supply system on the premise of ensuring the normal operation of the locomotive in the system. Therefore, a CVR simulation model for direct supply TPSS is proposed in this paper. The model analyzes the energy saving of the whole system by reducing the secondary voltage of the transformer. Simulation results show that the application of CVR technology in traction power supply system is feasible and effective.