As a powerful flexible AC transmission equipment,Unified Power Flow Controller (UPFC) has been further extended in the domestic power system and gradually applied in the 500 kV level system,circuit breaker protection in the 3/2 connecting mode of transmission line with UPFC will face new application problems.Based on the Southern SuZhou power grid 500 kV UPFC demonstration project,this paper analysis the circuit breaker protection device's special functional requirements in power system with UPFC.According to different connecting modes,the adaptability of circuit breaker protection and the combination strategy of circuit breaker protection and UPFC control protection in three phase inconsistent operation are proposed.All of this can effectively avoid the reclosing of circuit breaker protection with UPFC.The research improves operation reliability of UPFC system.