Abstract: First, according to the data of mineral pressure observation, this paper analyzes the characteristic of the initial support force, the working resistance, the late resistance etc. And find that the eigenvalue of hydraulic support is relatively small. The paper establishes the mechanical model of hydraulic support and the interaction model of support and roof, the analysis results of which show that the working condition of hydraulic support is related with special roof structure. The results show that during the normal stoping, due to the thickness of the quartz sandstone, the basic roof subsides hardly. Then the support bears the load of immediate roof approximately. During the periodic weighting, due to the thickness and hardness of basic roof and stuffed goaf, the given deformation of basic roof is small. It makes the ground pressure strength small.