The seam crack point of multiple branch seam fracturing is not clear. Based on the theory of porous media of fluid solid coupling mode, Comsol software was used to simulate branch seam fracturing process using finite element simulation. The changing law of stress concentration of seam crack point and shaft crack point was analysized under the condition of different stress difference it was found that with the increase of net pressure on the seam, there was a difference which distinguished between crack priorities. By controlling the net pressure change within joint, the crack priorities was adjusted, the number of multi branch fracture was controlled, and the multi branch seam hydraulic pressure of the complexity of the fracture network was ensured. Calculation analysis of hailaer oil field on the spot was used to adjust the net pressure inside seam. The result of construction was same with simulation, and can be used to guide the construction to improve the success rate of multi branch seam hydraulic fracturing.