Abstract:Putting veneer cover soil on the slope of expansive soil subgrade is a method to prevent the failure of ex2 pansive soil subgrade. But the interface between the veneer cover soil and the subgrade becomes a new weak2point to whole subgrade. This leads to another stability problem of veneer cover soil it self . To analyse the stability of ve2 neer cover soil of equal2thickness , the most commonly used methods are based on the assumption that slopes are in2 finite in length. But the practical slopes of subgrade are finite in length. Through laboratory testing study , it is found that the actual sliding surface occurs in veneer cover soil on finite slope , which is different f rom the result s commonly used methods mentioned above. According to the actual sliding surface f rom laboratory testing study , a new formula is developed to determine the stability factor of veneer cover soil on the slope of expansive soil sub2 grade.