Abstract: Station power supply system is the guarantee of substation operation, monitoring and communication, and also the basis of normal operation of power grid equipment and correct signal transmission. Due to the aging of equipment in some substation power system and unreliable access to UPS power supply, two channels of dispatching data network may exit when a system failure trip occurs, resulting in the interruption of substation signal upload, which affects the monitoring duty personnel's analysis and handle trip accidents. This paper firstly analyzes the communication channel exit case caused by a 10 kV line fault trip, and then conducts correlation statistics on the double-channel exit events caused by the substation line trip in Xuzhou area, and finally puts forward improvements and countermeasures.