From 1974 to 1993, 20 patients with dislocation of patella in 26 knees were treated by surgical technique, including 11 males and 9 females, aged from 10 to 67,averaged 31 year old. Thirteen cases (16 knees) were available for followup with an average period of 6.4 years. Using the criteria of Insall, the result were excellent in 5 knees, good in 5 knees, fair in 3 knees and poor in 3 knees with a success rate of 62%. Based on the biomechanism of patella movement and the findings in this study, the mechanism of dislocation of patella and its biomechanical reconstruction principle as well as the factors influencing the operative results were discussed.