After total hip arthroplasty, the stress shielding effect can occur due to the difference of stiffness between the metallic alloy of the stems and the host bone, which may cause a proximal bone loss. To overcome this problem, a low-modulus metastable β Ti-20Zr-3Mo-3Sn alloy composition has recently been designed to be potentially used for the cementless femoral hip stems. After having verified experimentally that the β alloy has a low modulus of around 50 GPa, a finite element analysis was performed on a Ti-20Zr-3Mo-3Sn alloy hip prosthesis model to evaluate the influence of a reduced modulus on stress shielding and stress fields in both stem and bone compared with the medical grade Ti-6Al-4V alloy whose elastic modulus reached 110 GPa. Our results show that the Ti-20Zr-3Mo-3Sn stem with low elastic modulus can effectively reduce the total stress shielding by 45.5% compared to the common Ti-6Al-4V prosthesis. Moreover, it is highlighted that the material elasticity affects the stress distribution in the implant, especially near the bone-stem interfaces.