Abstract: Aiming at the stability of the artificial dam,taking Lijiahao coal mine underground reservoir as the engineer- ing background,based on Drucker-Prager criterion,this paper researches the limit head value and the easy damage po- sition about the artificial dam. Results show that where the DP peak appear in is the surface of dam body and the mid- point of the outer surface,and the DP peak of the outer surface is larger than the inner surface. The value of the DP peak is biggest in the outer surface of bottom midpoint,followed by the top side of the midpoint,on the both sides of the center point,the minimum peak,and both sides at the midpoint of peak is approximately symmetrical. The midpoint of the outer surface of the bottom edge is the most prone to failure location. Further study finds that the limit head is the 17. 8 m of the artificial dam,and the result of the Comsol numerical simulation and field test data are obtained.