Abstract: The fog rain has an effect on the seepage field of landslides.The effect involves a series of complex problems,such as intensity decision of the fog rain,surface flow and saturated-unsaturated seepage analysis of the landslides,etc.The fog rain’s intensity of the Dayantang landslide,which is located at the Shuibuya project,is obtained with the fuzzy comprehensive evaluation method.The soil-water characteristic curve is determined with tests,and the variable regulations of the seepage field in the landslide is gained with sloping surface run off-unsaturated seepage coupled numerical method.The results provide a seepage field condition used to forecast the stability of the Dayangtang landslide.The research methods offer a new way for simulating unsaturated seepage field of the landslide under the condition of fog rain or rainfall.