Abstract: This study addresses the root fracture issue of the oil pump discharge valve seat connector under combined dynamic impact and static tensile loads. A three-dimensional finite element model of the valve ball-valve seat-valve seat connector was established using SolidWorks and ANSYS/LS-DYNA to conduct a multi-scale study of mechanical behaviors. Through explicit dynamics and static analysis, it was found that the maximum equivalent stress in the right-angle transition zone at the connector root reaches 516.8 MPa, indicating severe stress concentration. Structural improvements through fillet radius optimization （R=1 mm） and wall thickness increase （2.5→4.5 mm） reduced the stress peak to 184.74 MPa （64.2% reduction）, increased the sectional moment of inertia by 117%, and achieved more uniform stress distribution. The results demonstrate that the composite optimization strategy significantly enhances the connector’s fatigue resistance by dispersing stress concentration and improving bending stiffness, providing theoretical guidance for improving high-pressure sealing structures in downhole operations.