Abstract: In order to assess effect of using coal seam water injection to control strong pressure of No.3 coal seam of Zhaozhuang Coal Mine, pre-evaluation research of using coal seam water injection to control strong pressure was carried out. Water injection parameters including moisture content, water absorption, firmness coefficient of coal sample and so on were tested to analyze feasibility of water injection of No.3 coal seam. Absolute variation and change rate of compressive strength of test sample before and after soaking were test to analyze expected pressure-relief effect of water injection and propose injection project. The analysis result shows that No.3 coal seam can meet the conditions of water injection, and after soaking, physical properties of coal and rock samples are changed, compressive strength is reduced greatly, which indicates water injection has desired expected pressure-relief effect.