Objective To investigate the edge contact behavior of conformal spherical hip joint replacements under the given dynamic contact displacement condition. Methods Based on the developed spherical-grid-data model, the contact behavior and corresponding edge contact behavior of a typical metal-on-metal hip joint replacement was simulated under the increasing displacement between the acetabular cup and femoral head. Results It was found from the obtained results that the vertical and horizontal component of the support force due to contact pressure increased with the dynamic contact displacement increasing. The vertical component of support force for the edge contact showed a slower variation tendency than that for the non edge contact, while the corresponding horizontal component of support force increased more significantly with the dynamic displacement. In addition, the corresponding contact pressure distributions and the contact areas of hip joint replacements for edge contact and non-edge contact were different. Conclusions The significant edge contact behavior of hip joint replacements with bigger cup inclination angle occurrs with the increasing displacement of femoral head to the acetabular cup, which will cause the sliding between contact surfaces and additional wear since the horizontal support force increases. This provides a reference for the wear assessment and manufacturing of hip joint replacements.