Abstract: An aerosol entrainment model under severe accident conditions was developed in the three-dimensional computational fluid dynamics（CFD） containment program GASFLOW. The phenomenon of aerosol entrainment caused by containment pressure relief was analyzed in two containment atmospheres, air-steam and pure steam, and the results were compared with Ishii model calculation results and REVENT test data under the same conditions. The calculation results show that the developed aerosol entrainment model can well simulate the aerosol entrainment behavior.