Abstract: This paper,on the basis of an analysis of the variant and water pressure trends monitoring record data of E1000 side slope of the Fushun Western Open pit Coal Mine,establishes the two layers seepage flow analysing and computing model;in the light of the flow balancing principle and FEM computer simulation,makes an analogue calculation and dynamic simulation of such values as penetration of rain fall into the side slope,the sink water volume of the alluvial deposit,the flow of water in the drainage well and drain holes;and puts forward a drainage and pressure reduction scheme of real significance.Practice indicates the effect is favorable.