Abstract: In order to obtain the initiation pressure and infiltration and diffusion distance of the Jurassic coal seam in northern Shaanxi Province, testing water injection of coal seam with high-pressure and low-flow pump or low-pressure and high-flow pump, the paper analyzes and contrasts the initiation pressure, water diffusion distance and water injection amount. The results show that the initiation pressure of coal water injection is mainly controlled by horizontal bedding, and the initiation pressure is basically consistent with the shear strength of coal seam; the water diffusion distance is 17 m to 21 m along the horizontal bedding; as the water injection length increases, the water diffusion distance is gradually reduced; water spreads along the main bedding and fractures and connects the secondary fractures to further wet and soften the hard seam and increase the water content of coal and reduce the coal dust in the production process.