Abstract: Based on the site measured roof deformation law of the mine roadway,a more closed actual complex roof idea of the mine seam gateway was provided.S upposing the deformation curvature of each rock stratum before the complex roof of the seam gateway failed and in the failure critical status were same,the load on the roof was distributed to each rock stratum and thus the stressed condition of each rock stratum in the complex roof could be analyzed.According to the analysis on the st ressed features of the complex roof and the deformation failure law,it held that due to the soft and weak parting in the complex roof was low in strength and thin in thick ness,after the excavation of the mine roadway the parting would be failure firstly,the completed rigidity of the roof would be reduced,the roof structure would be weaken ed and thus a large secondary deformation would be occurred.If the roof could bear the load of the surrounding rock,the roof deformation would be stable steadily after the stress adjusted.If the roof could not bear the load of the surrounding rock,the roof would be seriously deformed and would be stability lost and failure after the stres s adjusted.The paper provided that the roof would have the deformation failure law with the structure load adjustment,structure rigidity weakening and structure stability lost.