One of the apparent characteristic of advanced PWR is the high reliability of passive safety system .It is important to assess the operation behavior of such system and the ability of system analysis code as RELAP5.One principal test facility, passive emergency core cooling system experiments is carried out. The RELAP5/Mod3.2 is used to simulated the experiments in this paper. The simulation capability of RELAP5/Mod3.2 in passive emergency core cooling system is assessed through the comparison between the experimental results and calculation results.