The snow-covered area is an important factor of the distributed hydrological model for arid area. In order to study the relationship between snow-covered area and runoff, this paper used the snow-covered area above the Yingxiongqiao station based on MODIS data. The characteristics of the snow-covered area in recent years were analyzed. The effect of precipitation and tem - perature variation on the snow-covered area was analyzed by using partial correlation analysis. The relationship between runoff and snow-covered, precipitation and temperature was studied by using multiple stepwise regression and path analysis. The results show that (1) the biggest and smallest snow-covered area appear in December and July; (2) the temperature is more sensitive to the change of snow-covered area; (3) the interaction between the various factors in the river basin promote the generation of runoff.