Under the condition of large inclined angle, the stability control of hydraulic support was always the challenge for the fully-mechanized mining in large inclined coal seams. Based on the specific geological conditions of 509 coalface with large inclined and high mining in Gaozhuang mine, the model of hydraulic support had been drawn by using SolidWorks software, and the inclination mechanical model of hydraulic support had been established to analyze its inclination stability along coalface. The calculation result shows that when the maximum inclination angle is 31° and the underhand angle is 10°, the minimum support resistance needed to keep the hydraulic support not dumping is 283.59 kN. Meanwhile, the critical support resistance required for the hydraulic support not to dump in inclination direction increases approximately linearly along with the increase of coalface mining height; under the same mining height condition, the critical support resistance increases along with the increase of the inclined angle. Therefore, the selection of the mining height and inclined angle of the coal seam must be considered at the beginning of the hydraulic support design.