Abstract: The passive containment cooling system (PCS) of the HPR1000 plays an important role in maintaining the containment integrity. The existing general severe accident integrated analysis program does not include a program module that simulates PCS, which is inadequate for the HPR1000 accident analysis. In this paper, the PCS program module was coupled with the integrated program to study the transient response characteristics of containment under severe accident conditions. The calculation results show that the temperature inside the containment with PCS is about 20 K lower than that without PCS; the pressure with PCS is about 7×104 Pa lower than that without PCS; the steam mass fraction of large space with PCS is about 0.1 lower than that without PCS. The coupling of PCS program module with the severe accident integrated analysis program makes up for the shortcomings of the integrated program in the accident analysis of the HPR1000 and is of great importance to the accident analysis. Meanwhile, the above calculation results verify that PCS can significantly remove the heat and reduce the pressure inside the containment, which helps to maintain the containment integrity.