Abstract: Loess in China is distributed in the seasonal frozen soil area.Effect of Freezing-thawing has greatly influenced on the stability of loess slope which has special structure,impel a large number of loess hazards.Study on Freezing-thawing mechanism,has some important theoretical and practical significance to reduce loess slope hazards.According to the characters of loess slope and Freezing-thawing,use numerical simulation of the surface freezing temperature,analysis groundwater accumulation model before and after freezing,and analysis example,reveal freezing process on surface soil of slope and water accumulation,discuss the Freezing effect on slope surface and response on stability.The result is: (1)The Freezing effect begin from surface to inner,reach maximum depth about 3 months after the freezing; (2)Analysis the simple groundwater accumulation model,derive the equation of groundwater saturation line; (3)The stability of loess slope will reduce about 25% by the effect of freezing-thawing.