The mei-yu front heavy rainstorms occurred over Nanjing on 3-5 and 8-9 July 2003 and were simu-lated in this paper using the Weather Research and Fore-casting Model (WRFv3.1) with various mesoscale con-vection parameterization schemes (MCPSs). The simula-tions show that the temporal and spatial evolution and distribution of rainstorms can be modeled; however, there was incongruity between the comparative simulations of four different MCPSs and the observed data. These dis-parities were exhibited in the simulations of both the 24-hour surface rainfall total and the hourly precipitation rate. Further analysis revealed that the discrepancies of vertical velocity and the convective vorticity vector (CVV) between the four simulations were attributed to the devia-tion of rainfall values. In addition, the simulations show that the mid-scale convection, particularly the mesoscale convection system (MCS) formation, can be well simu-lated with the proper mesoscale convection parameteriza-tion schemes and may be a crucial factor of the mei-yu front heavy rainstorm. These results suggest that, in an effort to enhance simulation'and prediction of heavy rain-fall and rainstorms, subsequent studies should focus on the development and improvement of MCPS.