Abstract: The surface subsidence has great difference when fault exists in overburden strata. To study the influencing factors of abnormal surface subsidence, the mechanism of fault activation was built and the relationship between abnormal subsidence with fault dip,advancing working length,mining height,protective coal pillar and strength of filling material in fault zone were studied by numerical simulation.The result shows that the step subsidence and maximum subsidence will increase with the fault dip as well as the mining height.The step subsidence will increase with the advancing working length when the advancing direction is non-full mining,while it will not increase when the advancing direction is full mining.The step subsidence will decrease with the protective coal pillar width increasing.The strength of filling material in fault zone has small effect on the surface subsidence. The research result has great significance of analyzing surface subsidence laws when the fault exists in overburden strata.