Abstract: The switching devices in a distribution system can effectively improve the operational reliability of the system.The types of switching devices and their locations have great effects on the operational reliability of the distribution system.Given this background,the optimal placement strategy for switching devices is addressed taken the reliability indices into consideration.Firstly,the method of calculating the customers’ failure time under different contingencies is proposed.Subsequently,an optimal placement model for switching devices is presented to minimize the sum of investment cost,the operation and maintenance cost,as well as interruption cost of customers considering two reliability indices within tolerable thresholds respectively.Secondly,the proposed model is transformed into a mixed integer linear programming model by linearizing the interruption cost function,and then solved efficiently by commercial solvers.Finally,the proposed method is tested with the IEEE RBTS-Bus 4 distribution power system and an actual medium voltage distribution network.Simulation results illustrate the basic characteristics of the presented model and solving method.