Abstract: The analysis model for advanced pressurized water reactor was established by using mechanism analytical code. The model included reactor coolant system, engineering safety features and related secondary side pipes system. The typical small break loss of coolant accident and large break loss of coolant accident were selected to analyze the accident progression. The water injection capacity and cooling capacity of passive residual heat removal system (PRHRS), core makeup tank (CMT), accumulator (ACC), automatic depressurization system (ADS) and in-containment reactor water storage tank (IRWST) included in passive core cooling system (PXS) were focused on for LOCA with different sizes and locations. The results show that the size and location of break have an influence on the accident progression. But the peak cladding surface temperature does not exceed 1 477 K and the reactor core is flooded underwater in all the accident conditions. The PXS can effectively remove reactor core decay heat and keep the reactor in the safe shutdown situation to prevent severe accident.