Abstract: PWRCPS is a program system of PWR criticality calculation. The 69 multi-group constants li-brary, the multi--group spectrum module, the assembly group parameters module and the reactor criti-cality module are combined into the program system by the INTERFACE program, so the programoperation is convenient. The correctness of interface among the modules is verified by the PWR criti-cality calculations. The total CPU time is less then 1500s for the PWR criticality calculations of tendifferent cases, the run speed is fast.