To reduce the system’s interruption frequency, a coordinated optimization method for load switches and circuit breakers in a distribution network is proposed, with the system’s average interruption frequency introduced as a constraint. By considering the uncertainty of distributed generation and load, a sample matrix is generated using Latin hypercube sampling, and the uncertainty problem is transformed into a deterministic problem by applying a multi-scenario analysis method. To improve the efficiency of island partitioning, a heuristic method is proposed to determine the scope of islands. Case analysis is carried out on an improved IEEE RBTS-BUS6 F4 distribution system. The results show that configuring a proper number of circuit breakers among the switches can satisfy specific interruption frequency requirements and improve the supply availability of the system. Furthermore, the optimal switch allocation scheme that considers source-load uncertainty demonstrates better robustness.