Abstract: In order to analyze the rock pressure law of thick coal seam caving mining in Qinshui coalfield, the author took the 3309 caving mining face in Wangpo coal mine as an example, and used the roof pressure on-line monitoring system to record the periodical weighting, the change of the working resistance of the hydraulic support column, the force of the vertical column and the opening of the safety valve. In this paper, the periodic pressure law of the roof of the caving mining face in thick coal seam was analyzed, and the safety protection measures for the working face before the periodic pressure were put forward, which provided the basis for the roof pressure control in the mining face of the coal mine in the adjacent coal mine in the Qinshui coalfield.