Abstract: In order to understand the transient response characteristics of the passive containment cooling system, the passive core cooling system and the passive residual heat removal system after the small break LOCA in an advanced pressurized water reactor, the coupling response characteristics of the reactor coolant system and the containment in SBLOCA are studied. The analysis results show that in the SBLOCA, the characteristics of the passive residual heat removal system, the passive core cooling system and the passive containment cooling system in the coupling analysis are quite different from the independent calculations. The containment peak pressure obtained by the coupling analysis in the SBLOCA is less than that by the independent calculation.