Abstract: In order to effectively prevent mine earthquake induced by key strata movement in the gob，and according to actual data in the field，the size of fracture region in overlying key strata of the gob is simulated with application of the finite element numerical simulation software.Accordingly，the cause for influencing the earthquake magnitude of 103up04 working face in Baodian coal mine is:fracture and instability of key strata which constituted by fine standstone and middle standstone that are hard or dense at the coal seam floor about 100~220 m，and the size of the fracture region corresponds to the earthquake magnitude.Based on the occurrence of actual magnitude in the 103up04 coal face，the preventing measures are put forward:the deep hole large diameter blasting at the behind of coal face is applied to improve the stress state of rock mass and a large amount of elastic energy accumulated in key strata is released.Thid method can effectively stop the whole movement of key strata，thus，reduce the occurrence frequency of disaster and the intensity of the mine earthquake.

Key words: Key strata, Fracture region, Mine earthquake magnitude, Suspending roof, Deep hole large diameter blasting