Seven fresh corpse knee joint were used to simulate excessive lateral patellar tilt by tighting thelateral patellar retinaculum, then the sagittal patellar osteotomy was performed at four differentosteotomy angles. The load was 200N. The contact area and pressure was measured at normalstatus, patellar tilting, 5 degree, 10 degree, 15 degree, 20 degree of osteotomy angle using Fujipressure sensitive film. The patellar tilt angle was gauged on patellar axial film of 45 degree of kneeflexion.The results showed that the contact area and pressure decreased in medial patellar surface,and increased in lateral patellar surface while patel1ar tilt occured. This alteration was mostprominent at 30 degree of knee flexion. After patellar sagittal osteotomy,the contact pressuredistribution of patellar tilt was improved markedly at more than 10 degree of sagittal patellarosteotomy angle. The 15 degree of osteotomy angle was the best to improve the distribution ofcontact pressue while patellar tilt existed. The results offered a reliable evidence for application ofsagittal patellar osteotomy and the selection of osteotomy angle.