Abstract: Regenerative braking energy utilization system plays an important role in the recovery and utilization of renewable energy, energy saving and carbon reduction of electrified railway. However, the regenerative braking energy utilization system based on power flow control technology will change the original power flow of traction power supply system, and its fault protection is very important to ensure the safety of electrified railway operation. Therefore, this paper studies the fault protection scheme of regenerative braking utilization system of electrified railway. Firstly, according to the operation principle of regenerative braking energy utilization system, the influence of system access on the existing protection of traction power supply system is analyzed. Then, combined with the impact analysis results, a protection scheme of regenerative braking energy utilization system based on the principle of "fault-oriented safety" is proposed. In this scheme, the graded protection strategy is formulated for different types of system faults. On this basis, the operation safety of regenerative braking energy utilization system is guaranteed through the coordination of system self-protection and existing protection of traction power supply system. Finally, two typical application cases of traction substation and section post are selected to verify the proposed protection scheme. The results show that the proposed protection scheme can effectively protect the regenerative braking energy utilization system in different application cases and ensure the safe utilization of regenerative braking energy..