Abstract: This paper presents a groundwater pollution mathematic model on the ash lagoon of thermal power plant. Simulating groundwater quality adopts the Euler - Lagrange viewpoint, characteristic line method and 9 - node high - order finite element interpolation; and simulating groundwater flow adopts a new mixed finite element method. So this model has high precision. The transport, dispersion and concentration variation of the F-, So42-constituents of ash in groundwater were predicted as long as twenty years for Heze power plant.