Based on the multiple observations and WRF model, a Mesoscale Convective System (MCS) process occurred on 7 August 2016 in Huaibei area was simulated and diagnostically analyzed. Results show that:firstly, the MCS process happens under weak weather scale forcing with weak systemic upwelling, coupling with weak water vapor transportation by the east to southeast winds, which originated from the Northwest Pacific Ocean in the lower troposphere. Secondly, the movement and deformation of MCS are consistent with the evolution characteristics of surface convergence line, and the evolution of surface flow field is closely related to the rainfall intensity.Thirdly,the distribution characteristics of precipitation and the interaction between convective activities and the ground convergence line during the evolution of MCS are reasonably simulated by WRF model. Finally, the simulation results indicate that the MCS has completed the replacement of convective cells during the gradual southward movement, meanwhile the surface convergence line plays an important role in this process. Besides, differences can be seen in the vertical distribution of convective instability in the environmental field of convective monomers at different stages of development.