Objective To explore the effect of hip surface replacement on the mechanical characteristics of proximal femur.Method Eight cases of young fresh normal femoral specimens were selected and one leg in standing position was used in the measurement.The biomechanical test was performed on the WD-5 type machine to detect the relation of loading and strain,distribution of stress,rigidity,torsion of normal proximal femur and resurfaced proximal femur under the loading of 1000N.Result No significant difference was found in the relation of loading and strain,distribution of stress and rigidity between normal proximal femur and proximal femur with surface replacement.The maximal torsion between normal proximal femur and proximal femur with surface replacement was 19%,which showed significant differences.Conclusion The hip surface replacement could maintain normal transfer of load to the proximal femur,and avoid resorption resulting from stress shielding similar to THA,therefore it can preserve the proximal bone stock around femoral stem and make the consequent revision easy.It is an effective solution suitable for young patients.