Abstract: Taking the ash yard of a power plant as an example, the stability of the ash disposaldam of the thermal power plant is calculated by the finite element strength reduction method and rigid body limit equilibrium method.The research shows that the groundwater in the ash disposal dambody will not flow out from the outer slope regardless of the current water level or the water level at the final disposal capacity.The ash disposaldam is stable when the current conditions and ash disposal capacity reach the designed capacity, and can meet the requirements for safe operation of the ash yard.It is recommended to observe the groundwater saturation line in the ash disposaldam and strengthen the inspection of the slope surface of the dambody.