A method for protection switching decision includes: performing performance monitoring and failure detection on a first transmitting entity that transmits services; performing performance monitoring and failure detection on a second transmitting entity that does not transmit services; and making protection switching decision according to the performance monitoring and failure detection results of the first transmitting entity and second transmitting entity. A system for performance monitoring is also disclosed. In embodiments of the present invention, performance monitoring can be performed on the transmitting entity that does not transmit services, thus avoiding invalid switching of services and improving the quality of services.