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The rock mass is change during mining, according to their evolutionary characteristics, the model of movement and destruction of rock mass was built up. Then the authors researched on the correlation between attenuation index of mass subsidence factor and the breaking number of unit length rock according to the law of the rock mass rupture. After that, we gained the functional relationship between the fracture length of rock mass and the mining height by regression fitting using of underground measurement data of field observation, at the while, we derived to confirm the relationship formula of subsidence factor with the mining height and influence coefficient of lithology. The results show that the subsidence factor decreases with the increase of the mining height, which approximately presents the negative logarithmic function relationship between them, and under different lithology, subsidence factor has different value; the harder the mass, the smaller the value, vice versa. [ABSTRACT FROM AUTHOR]