A knee joint prosthesis pad three-dimensional force sensor and a contact stress measurement method. The knee joint prosthesis pad three-dimensional force sensor may be applied between the tibiofemoral joints, and comprises a middle flexible elastic layer (10), an upper hard layer (20) and a lower hard layer (30). The middle flexible elastic layer (10) has an upper curved surface (101) and a lower curved surface (102). Several sensing elements (40) are provided on the upper curved surface (101) or the lower curved surface (102). The shape of the upper hard layer (20) matches the shape of the upper curved surface (101) and is attached onto the upper curved surface (101)； and the shape of the lower hard layer (30) matches the shape of the lower curved surface (102) and is attached onto the lower curved surface (102). The magnitude, direction and position of the resultant force of contact forces between the tibiofemoral joint may be calculated by means of an algorithm, so that the measured numerical value is more accurate and the resultant force in the three-dimensional direction of contact stress of the joint may be calculated, thereby reflecting more realistic stress distribution, and providing quantitative guidance for doctors to determine the inter-articular force distribution circumstance and a soft tissue balancing link.L'invention concerne un capteur de force tridimensionnelle de coussinet de prothèse articulaire de genou et un procédé de mesure de contrainte de contact. Le capteur de force tridimensionnelle de coussinet de prothèse articulaire de genou peut être appliqué entre les articulations tibio-fémorales, et comprend une couche élastique souple intermédiaire (10), une couche dure supérieure (20), et une couche dure inférieure (30). La couche élastique souple intermédiaire (10) a une surface incurvée supérieure (101) et une surface incurvée inférieure (102). Plusieurs éléments de détection (40) sont disposés sur la surface incurvée supérieure (101) ou la su
