Objective To measure the three-dimensional motion of the knee joint in healthy individuals and patients after TKA (Total Knee Arthroplasty). Method This study combines biplane high-speed photography with the theory of human knee joint motion analysis to propose a kinematic measurement technique for the knee joint based on biplane high-speed photography. Results The results indicate that at the flexion angle of the femur relative to the tibia, the peak value of the artificial knee joint is lower than that of the natural knee joint. However, in terms of abduction, external rotation, lateral displacement, and posterior displacement, the peak values for the artificial knee joint are 14.8°, 22.3°, 12mm, and 15.7mm, respectively, which are greater than the natural knee joint""s 6°, 10°, 3mm, and 11mm. Additionally, in terms of proximal and distal movement, the artificial knee joint moves towards the proximal end, while the natural knee joint moves in the opposite direction, with the peak value for the artificial knee joint being 12.6mm, greater than the natural knee joint""s 3.5mm. Conclusion By comparing the kinematic parameters of the knee joint and comparing different measurement techniques, it can be seen that biplane high-speed radiography technology is effective in the measurement of knee joint kinematics and can provide technical support for in vivo measurement of three-dimensional knee motion.