Rainfall, especially heavy rainfall (torrential rain), has great impact on economy, society and people's routine life. While owing to the complicated physical processes related to rainfall, the studies and predictions of rainfall are rather difficult. Previous relevant studies mainly focused on the impacts of water vapor and its convergence. Gao et al.(2005a) proposed a so-called surface rainfall equation by combining the tendency equations of water vapor and hydrometeors (cloud water, rain water, cloud ice, snow and graupel), which can be used to study quantitatively the water vapor variation and cloud evolution related to surface rainfall together.  In this article, 21-day tropical cloud-resolving simulation data are used to calculate the local change and convergence rates of water vapor, surface evaporation rate and cloud variation rates in the surface rainfall equation, and their impacts on surface rainfall are discussed. The results show that local change rates of water vapor and cloud hydrometeors, water vapor convergence rate and surface evaporation rate all have great influence on surface rainfall. The co-existence of water vapor convergence and local vapor loss leads to heavy rainfall, and the co-existences of water vapor convergence and local vapor gain or water vapor divergence and local vapor loss lead to medium rainfall, and the co-existence of water vapor divergence and local vapor gain leads to weak rainfall. The partition of convective and stratiform rainfalls shows that the convective rain rate is normally bigger than the stratiform rain rate. Water vapor convergence is the main water vapor source for convective rainfall, while local vapor loss is the main vapor source for stratiform rainfall. Model domain mean local vapor loss mainly occurs in the raining stratiform region, while the strongest local vapor gain occurs in the convective and clear sky regions. The strongest local hydrometeor loss occurs in the stratiform region, while the strongest local hydrometeor gain occurs in the convective region.