In order to study the influence degree of rainfall intensity on the instability of superficial slope, based on the detailed geological survey in the field, the Geostudio software is used to simulate the seepage field and stability of the slope under different rainfall conditions, and study the stability coefficient and instability probability under the corresponding working conditions. then, the risk assessment of the slope under extremely unstable conditions through the quantitative method is carried out. The results show that the slope is only vulnerable to instability under fully saturated conditions. The probability of instability is as high as 48.93%. The total value of the disaster-bearing body in the landslide-affected area is 3.619 million yuan, the annual loss of property is 0.8324 million yuan, and the probability of single-person annual death is 8.7^*10^-2, which is in the extremely high risk area.