Loading on imitative tibiofemoral joint of a flexed knee in 0°,10°,20°and 30°,which is made of photoelastic material. The result shows that the tibiofemoral touching area of internal condyle is larger than external condyle, the stress distrbution of external condyle is stronger than internal condyle, the strongest stress distribution is on the area of touching centre. With the angle of flexed knee joint goes larger, (1) the centre point moves backward, within 30°,the slide rate of internal side is 40.23%, external side is 45.92%;(2)two centre points of tibial plateau move medially,the distance between the centre points is enlarged; (3) tibiofemoral touching area decreases; (4) the peak value of stress increases, the increasing rate is far higher than decreaseing rate in area. The result of the experiment points out that for correcting knee deformity, recovering the normal tibiofemoral para-position and stress distribution should be paid more attention.