Horizon slope is strata towards the slope strike vertical which is a good overall stability slope under natural state,In large-scale earthquake disaster areas of Wenchun County,it could found that instability model of horizontal slope under intensive earthquake are tension-crushing by large landslide survey.Instability mode is tension-trushing slippery under intensive earthquake.Based on Xinping village,Pingwu County landslide as an example,slope edge at the interface between tensile stress appears under the intensive earthquake,and the cracks apper unceasingly deepened,lower slope body appears stretch shear destruction because of the vertical and horizontal vibration,thus forming a uniform sliding surface,the crushing slippery slope body then cracks and slides down as "granular mixture" which rushes to slope bottom margin of peasant caused 9 villagers deaths,and it enters Zhengjia ditch blocked by the opposite mountain,then it moves like post-concussion and forms a barrier lake.These achievements are update in a certain sense to the traditional concept of stability evaluation of the horizontal slope.