Objective To evaluate biomechanical strength of locking compression plate (LCP) for fixation of periprosthetic proximal femur fractures (PPFF). Methods Eight matched pairs of Vancouver type B1 adult cadaveric PPFF specimens were fixed with the LCP and inverted distal femoral less invasive stabilization system (LISS) respectively. Four bicortical locking screws (LCP group) and four unicortical locking screws were used to the length of prosthesis stem, and 4 double cortical locking screws were used to fix the distal end of the fracture in two groups, the distance from the locking screws to the fracture were also equal. Four point bending test and torsion test were performed until the internal fixation failed. The bending stiffness and the torsional stiffness of LCP group and LISS group were calculated from the linear curve of bending load- bending displacement and torque- torsional angle. The paired t -test was used to analyze the maximum bending load, maximum bending displacement, bending stiffness, maximum torque, maximum torsional angle and torsional stiffness of two groups. Results The maximum bending load, maximum bending displacement and bending stiffness of LCP group were all higher than those with LISS, but the difference was not statistically significant (P > 0.05). The maximum torque, maximum torsional angle and torsional stiffness of LCP group were obviously larger than LISS group，there was a statistical difference between two groups (P < 0.05). Conclusion The stiffness of anti-torsion with LCP was significantly better than that of LISS. Consequently, LCP have better biomechanical stability for PPFF.