In order to study the response of granite residual soil slope with cracks under different number of drying-wetting cycles (D-W cycles), model test was carried out and the crack width expansion index was quantified by investigating the crack images. Based on the direct shear test, the calculation formulas of soil strength degradation and crack depth were developed. Then, the model test and the numerical simulation results were compared to analyze the response of the residual soil slope considering crack extension. The results showed that the fractures width expansion in residual soil under D-W cycles followed the Logistic model, and there was a quantitative relationship between fracture depth and strength degradation. The fracture depth tended to be stable with the increase of D-W cycles. When the number of D-W cycles was small, the change of moisture content at the bottom of the slope lags significantly behind that at the top and the middle of the slope, however, the change of moisture content at each position of the slope tended to be the same with the increase of D-W cycles. The deformation at the bottom and the middle of the slope with the crack expansion tended to be the same compared to the slope without cracks, however, the deformation at the top area was larger, which led to the increase of the deformation gap between the top and bottom of the cracked slope.