Landslides are the downslope mass movement caused by gravity on hillsides. In this study, we developed a landslide model that describes a block sliding down an infinite slope governed by Newton’s equation of motion, considering the block weights, its internal excess pore pressure and friction. This numerical model considers pore pressure evolution within a soil layer under rain infiltration obeys diffusion equation, numerically solved by the Chebyshev polynomial method. Results show that the critical soil-layer slope, critical excess pore pressure, and the time to reaching landslide occurrence are controlled by soil properties and rainfall infiltration intensity. We also investigated the effects of rainfall infiltration characteristics and the variation of groundwater level on landslide triggering.