Abstract:  In order to research the process of roof caving and fracturing over a longwall panel which is beneath a goaf mined by room and pillar method，physical analog simulation has been built up in condition of geological situation of Tangshangou coal mine.In this physical model，the subsidence velocities of roof and strata fracturing have been obtained．After the subsidence velocities have been differentiated，we got the acceleration of subsidence in such kind of geological and mining condition．The data shows that the overburden released energy with a short step periodically．By the way，the larger energy released after a several short step．During this process the strata began to fracture，and especially，the pillar collapsed quickly in a goaf mined by room and pillar method．The caving process started from pillar and roof to the surface quickly．The fracturing speed of strata is quicker than one in a virgin overburden.

Key words:  , physical analog simulation；goaf mined with room and pillar method；roof caving；subsidence velocity；mining-induced fractures