Background: Unicompartmental replacement is the first choice in the gradient treatment of late reconstruction of knee arthritis. The interface stress of cemented tibial prosthesis has a significant impact on prosthesis loosening and prosthesis life after unicompartmental replacement, but there is a lack of research on it. Objective: To analyze the interface stress of tibial prosthesis platform and determine the stress injury area, so as to provide reference for the stress failure of tibial platform in clinical single condylar replacement.Methods: The full cycle gait was simulated by human dynamics software to obtain the load-bearing condition of knee joint; A complete model of knee joint was established by medical imaging and three-dimensional reconstruction software, and unicompartmental replacement was performed; The distribution of interfacial stress of tibial prosthesis platform after single condylar replacement was analyzed by finite element method.Results: In gait, the force and angle of knee joint change periodically with time, 1.3s is a cycle, and the peak of knee joint resultant force is 760n; The maximum shear stress of the interface was 11.82 MPa and the maximum tensile stress was 6.849 MPa, both occurred at the prosthesis cement interface, and occurred at the corner of the inner front end of the interface; The maximum interface stress of titanium alloy prosthesis is lower than that of stainless steel prosthesis. Conclusions: The decrease of elastic modulus of prosthesis can reduce the maximum principal stress at the interface. Considering the interface stress, titanium alloy prosthesis is better than stainless steel prosthesis; Therefore, improving the ability of prosthesis cement bonding in this area can prevent the loosening of tibial prosthesis of unicompartmental knee joint.