Abstract: The environment of groundwater is vulnerable in the area of Guizhou with complex karst． It is important to march groundwater pollution risk assessment in reality． The groundwater pollution by ash field in a power factory of coal-electricity integration in Southwest Guizhou Province has been taken as an example for risk assessment． The documents such as depth o groundwater，aquifer media，vadose zone media，vegetation distribution，pollution mode and function of groundwater has been collected． According to the groundwater characteristics in karst area and the influence of groundwater environment from ash， the groundwater pollution risk assessment index system of ash field in karst area has been built． The AHP method has been applied to calculate the weight of all index and total score of risk． The results showed the total score of risk was 2. 7295，which was not high within the low-risk range． This method had potential applicability for groundwater risk assessment on ash field， which provided a reference for field location in karst area and controlling seepage．