Abstract: The progressive damage model based on 3D Hashin failure criteria was established to investigate the structural connection failure behavior of a rocket motor composite case with full open polar. The connection failure mechanism and destructive behavior of the composite case were revealed. The failure modes, destructive location and destructive pressure were predicted precisely by the progressive damage analysis. Simultaneously, the hydraulic bursting test of the composite case was carried out to evaluate the reliability of the progressive damage model. The results show that the row screws fracture due to the enough axial shear strength for the full open polar and composite layers near the holes are compressive extremely serious result in fiber compression failure and large-scale delamination failure. Because of these, a sharp decrease in load-bearing capacity of the fiber, which leads to fiber fracture. Finally, the destruction occurs in the connection area of the case with full open polar. According to the experimental and simulation results, compared to the destructive pressure of 15 MPa obtained by burst test, the predicted pressure is 13.7 MPa based on the finite element model and the error is 8.7%, which indicates that the simulation model of the composite case has good prediction accuracy.