By virtue of the water pressure formula proposed by the author previously combined with the theory of shear strength of unsaturated soil,an analytical safety factor formula for the rainfall-induced shallow landslide was proposed.The influencing factors of the shallow landslide were analyzed.The results show that the rainfall-induced shallow landslide is mainly due to the decrease of matric suction.The desaturation coefficient,antecedent-rainfall intensity,slope gradient and soil water storage capacity have significant effects on the rainfall-induced shallow landslide.The effect of the rainfall intensity on the stability of the slope is obvious only when the rainfall intensity is large,while the saturated permeability would affect the shallow landslide significantly only when it approaches the rainfall intensity.