Abstract: The supporting problem of deep mining gateway is one of the key problems that must be solved in coal mining. The deep rock mass is subjected to a large horizontal tectonic stress, resulting in deformation of the roof under the combined action of the upper rock pressure and the horizontal tectonic stress. The deflection and maximum tensile stress formulae of roof are calculated by using the compression bending combination deformation of material mechanics, and the the results are used to design the turn airway of 40303 working face in Xiaozhuang Coal Mine. Field monitoring results show that the formula can be used to calculate the roof deformation and tensile stress. After the support optimization, the steep subsidence of the surrounding rock of the roof is controlled, and the good supporting effect is achieved.