Based on the WRF-simulated results, surface observation data, radar data, and the ECMWF ERA-5 reanalysis data, this paper analyzes the characteristics of local frontogenesis and its influence on the development of convective systems during the heavy rainstorm occurred on October 1—8, 2010, in Hainan Island. The results show that the environmental field played a major role in the frontogenesis process of this heavy rain event. The non-adiabatic heating term and the horizontal motion term contribute the most to the process of local frontogenesis, and the largest positive value area of the two overlaps many times in the heavy precipitation area, indicating that diabatic heating and horizontal deformation divergence are responsible for the strong frontogenesis in this area. In addition, the comparison and analysis of simulated results and observations show that the lower condensation height leads to strong latent heat release in the lower convective layer during the period of the strongest precipitation, and that the internal warming of the lower air mass in the convective zone creates a strong frontogenesis effect. The strong frontogenesis at the lower level accelerates the updraft, strengthens the development of deep convection, and intensifies the torrential rain. Compared with the diabatic heating term and the horizontal movement term, the contribution of the vertical motion tilting term related to vertical movement is small, but it increases at night. The analysis shows that the difference in the horizontal distribution of vertical velocity at night plays an important role in the enhancement of deep convection in areas with heavy rainfall.