The utility model discloses a relay protection system for in-phase power supply equipment, which mainly comprises a microcomputer protection device, a circuit breaker 1QF and a current transformer 1TA both arranged between an Alpha bus and the in-phase power supply equipment, a circuit breaker 2QF and a current transformer 2TA both arranged between a Beta bus and the in-phase power supply equipment, and two voltage transformers 1TV and 2TV respectively arranged on the Alpha and the Beta buses, wherein the current transformers 1TA and 2TA as well as the voltage transformers 1TV and 2TV are respectively connected with the microcomputer protection device. By adopting the relay protection system, the in-phase power supply equipment can be quickly cut off and isolated when a fault occurs, so that the continued damage to the equipment can be avoided, the fault-free part can be ensured to quickly recover into normal operation, and electrical energy can be continuously transmitted to an electric locomotive safely and reliably.