Objective To investigate biomechanical properties of the contact interface between residual limb and prosthetic socket of the transfemoral amputee during walking by using threedimensional (3D) finite element analysis method, so as to provide references for establishing the complete system of measurement, design and evaluation on prosthetic socket. Methods Based on CT images, two 3D geometric models of a trans-femoral amputee including the femur, soft tissues and transfemoral socket was established, with soft tissues defined as non-linear hyper-elastic and linear elastic material, respectively. The behaviors of the interface between trans-femoral residual limb and prosthetic socket were defined as nonlinear contact. Dynamic loads on the knee joint were applied on distal ends of both the hyper-elastic model and linear elastic model to simulate loading on residual limb-prosthetic socket system during heel strike, mid-stance and toe off phase in a gait cycle, respectively. The stress distributions on interface between trans-femoral residual limb and prosthetic socket were calculated to compare and analyze the effects of different mechanical properties (i.e. hyper-elasticity and linear elasticity) of the femur soft tissue on biomechanical behaviors of the interface. Results For both the hyper-elastic model and linear elastic model, the peak contact pressures were all located on the distal end of the residual femur during different gait phases. The peak contact pressure on the interface of the hyper-elastic model during heel strike, mid-stance and toe off phase was 55.80, 47.63 and 50.44 kPa, respectively, while that on linear elastic model was increased by two times, being 149.86, 118.55 and 139.68 kPa, respectively. Simulation on longitudinal and circumferential shear stress distributions at the limb-socket interface showed that stress on the interface was higher at the distal end of soft tissue during different gait phases. From heel strike to toe off phase, some pressures were transferred from the rear edge to the front edge of the socket. Conclusions The pressure and shear stress distributions on the contact interface between transfemoral residual limb and prosthetic socket were different during different gait phases, thus the relative mechanical properties should be considered in the socket design.