Abstract: Coal wall mechanical environment of high cutting face in steeply dipping seam is complex, coal wall easily instability, in order to better prevent and control coal wall instability, it is urgent to gain a clear idea of coal wall mechanics and deformation features. Analyzing coal wall mechanics, deformation features of 25221 high cutting face in steeply dipping seam by field measurement, numerical calculation and theoretical analysis methods, results show that abutment pressure in space with asymmetrical arch shell affects high coal wall of steeply dipping seam and decreases gradually in the form of curve in face advancing direction; non uniformity leading abutment pressure leads to the asymmetric deformation of coal, the horizontal displacement value within about 0 to 13m range ahead the face shows middle> lower> upper, the performance of over 13m is middle> upper> lower, the value performance of over 14.48m is middle> lower> upper, middle has the maximum displacement and deformation value, coal wall instability rate of the central region is largest; mining height increases, the degree of the lead abutment pressure concentration, coal deformation, displacement and large deformation range will increase.