An attempt is made to simulate the layer separation in overburden by using the finite element numerical modeling; and the numerical modeling together with similarity simulation is adopted to investigate the surface movement and the breakage of the overburden during the abandoned stope treatment of the section #143 in Mujia Hill. It has been found from this research that the range of surface movement increases moderately with the collapse of jambs and the increase of the roof span. The subsidence area ranges from 1.5 times to 1.7 times of the roof span and the subsidence curves are symmetrical to the vertical line through the point with maximum subsidence. The horizontal movement

however

is not symmetrical and its impacting area is larger than the range of subsidence

with its maximum value equal to 40 % of the maximum subsidence. In addition

the layer separation exists in the end of span of overburden if the subsidence happens in whole overburden，which is resulted from the shear failure of the bedding plane.