Abstract: Direct containment heating (DCH) is one of the major contributions to early overpressure of containment, which could threaten the containment integrity and lead to the early uncontrollable release of radioactive materials. In this study, one of the Gen Ⅲ PWR was selected as the research target. Firstly, a Fortran program with two-cell equilibrium (TCE) model and ROAAM was compiled to calculate DCH load for some typical sequences. Then, containment failure rate resulted from DCH was calculated for the typical sequences combined with containment failure probability curve. Finally, some parameters that are not easily to get in design phase or the reference research experience values were sorted out, the sensitivity analysis results were concluded, the uncertain factors of these parameter were found out. The study results reveal that the quality of melt core, geometric design of the reactor cavity, containment layout will affect the consequences of DCH directly.