Various scales of cracks occurred in the Tongma levee body during the construction of diaphragm wall. The stability of the riverside slope of the levee during the flood period is thus seriously concerned. This paper introduces the calculation process of the stability analysis under the condition of sudden drawdown of the water level. The selection of operating mode，cal culation parameters and the sensitivity analysis of strength parameters are mainly discussed. The result of this paper has provided basis for the engineering treatment to the levee cracks.