Abstract: Switchgears are widely used in distribution systems. To improve the reliability of power supply, the reliability of power distribution switches must be improved. The reliability of the controller on the distribution switch is inseparable from the safe and stable operation of the switching device itself. This paper takes into account the influence of the controller and proposes a reliability evaluation model based on fault tree analysis (FTA). The model traces down the root cause of the fault, finds the cause of the accident layer by layer, builds a fault tree. Based on this, this paper performs qualitative analysis, strong and weak correlation analysis, and quantitative analysis of the reliability of the switchgear and its controller. By analyzing the logical relationship between failures, calculate the reliability parameters. The analysis results are used to apportion the reliability index of the main cause of the failure of the distribution switch and its controller. Finally, this paper gives concrete suggestions for improving reliability based on the results of prorate calculation and simulation.