Abstract: Aiming at the root fracture problem of the oil pump delivery valve seat connector under combined dynamic impact and static tensile loads, this paper establishes a three-dimensional finite element model of the ball-valve seat-valve seat connector using SolidWorks and ANSYS/LS-DYNA, and conducts a multi-scale mechanical behavior study. Combining explicit dynamics and static analysis, it is found that the maximum equivalent stress in the right-angle transition zone at the joint root reaches 516.8 MPa, indicating severe stress concentration. Through structural optimization involving fillet optimization (R=1 mm) and wall thickness increase (from 2.5 to 4.5 mm), peak stress is reduced to 184.74 MPa (64.2% reduction), section moment of inertia is increased by 117%, the stress distribution tends to be uniform. The results show that combined optimization strategy can significantly improve the fatigue resistance of the connector by dispersing stress concentration and enhancing bending stiffness, providing a theoretical basis for the optimization of downhole high-pressure sealing structures.