Abstract: The nappe structures of Huainan coal field are developed on both south and north fringes of Huainan synclinorium,especially on the south fringe,The south fringe nappe is stronger and greater,and composed of serise of thrust faults which are of trend about EW and tendency towards S.On the section of the thrust,all of the faults presented upper steep and lower gentle and gradully combined to the same detachment fault at the lower position and constituted an overstep propagation thrust imbricate fan.The detachment fault is wavering both on the trend and tendency.The backthrusts on the north fringe might be produced passively under the tectonic action of the south fringe thrust.The results of macroscopic,microcosmic and super-microcosmic analyses all showed clearly that the scal and strength of deformation,and the enviroment of strain of the south fringe thrust are all higher than those of the north fringe thrust.But they are formed near at the same time.Thus this,the thrust imbricate tectonic system with the leading edge ceased at backthrusts is formed.