This study aimed to evaluate the biomechanical compatibility of a modular hemipelvic prosthesis by comparing stress distributions between an implanted pelvis and a healthy pelvis. Finite element analysis was used to simulate bilateral standing loads on both models, analyzing critical regions such as the sacroiliac joints, iliac crest, acetabulum, and prosthesis connection points. Six models with varied displacements of the hip joint rotational center were also introduced to assess the impact of deviations on stress distribution. The implanted pelvis had a stress distribution closely matching that of the intact pelvis, indicating that the prosthesis design maintained the biomechanical integrity of the pelvis. Stress patterns in displacement models with deviations of less than 10 mm were similar to the standard model, with only minor changes in stress magnitude. However, backward, upward, and inward deviations resulted in stress concentrations, particularly in the prosthesis connection points, increasing the likelihood of mechanical failure. The modular hemipelvic prosthesis demonstrated good biomechanical compatibility with minimal impact on pelvic stress distribution, even with moderate deviations in the hip joint's rotational center; outward, forward, and downward displacements are preferable to minimize stress concentration and prevent implant failure in cases where minor deviations in the rotational center are unavoidable during surgery.