Abstract: The movement,distorton and breaking rules of overburden,the evolution of damage in overburden,the bedding influence and the size characteristics of broken rock were studied by model tests.The evolution equation of damage in overburden was obtained.The bedding had greateffect on the subsidence.Because of the sandwich of terranes,it was different when overburden was distorted.The size of broken terrane was related to the rock strength.The scope of influence could be determined from mechanical parameters of terrane,and it was the basis for finding the micro-mechanism and the new predicting model of mining subsidence.