Objective To measure the three-dimensional (3D) motion of the knee joint in healthy people and patients after total knee arthroplasty (TKA). Methods The coordinate system for the tibia and femur of the knee joint was established, and the marking points were pasted at the bone landmarks. Then the 3D motion of human knee joint was measured by biplane high-speed photogrammetry, and the data were processed according to the coordinate transformation. Results The peak values of adduction and abduction, internal and external rotation, internal and external translation, and proximal and distal movement of the artificial knee joint were larger than those of the healthy knee joint (P<0.05), but there was no statitistic difference in posterior displacement between the artificial and healthy knee joints (P=0.05). Conclusions By measuring the knee joint motion, not only the difference in knee joint motion between the healthy volunteers and TKA patients was revealed, but also the effectiveness of biplane high-speed photography in knee joint kinematic measurement was demonstrated.