Abstract: In order to reduce large number of the measuring points in the site layout to observe the full process of the surface ground movement above the undergr ound seam mining,the FLAC3D software was applied to simulate and analyze the surface ground movement process caused by the seam mining in underground mine.T he paper held that the 50 steps method of the length calculation per 2 m excavation along the seam strike orientation could realize the longwall strike mining of the sea m.A simulation mining was conducted on a seam.There were 36 measuring points of the subsidence value and displacement speed set on the top surface of the model t hrough the mining center along the strike and inclined cross section line.The max subsidence value of the main cross section was 94 mm as obtained.The relationship C urve between the subsidence value and displacement of each monitoring and measuring as well as the displacement and the calculated steps could meet the curve of t he surface displacement knothe time function curve to improve.