Objective To explore the effect of the collateral ligaments and the plantar plate on the flexion of the metatarsophalangeal(MP) joints. Methods Twenty-four preserved human No.2-4 digits were obtained from embalmed cadaver feet, which were divided into 2 groups at random. In group A, the bilateral collateral ligaments were cut first, and then the plantar plate was sectioned. They were cut inopposite sequence in group B. Angle of the flexion of MP joint was observed in the same load after the bilateral collateral ligaments and the plantar plate were sectioned in different sequence.From 1994 to 2000,11 cases were used with this technic, including plantar section in 2 cases and both plantar section and bilateral collateral ligamentscut in 9 cases. Results The angle of flexion of the MP joint before operation in group A is 37.30±5.42°, it increased 11.29±2.36° and to 48.60±2.98° when the bilateral collateral ligaments were cut, and there was significant difference. Later the cut of the plantar plate increased another 5.30±1.59° and to 53.35±2.76°. Both have an increasing trend for the angle of flexion of the MP joint (Plt;0.01). While in group B, the angle of flexion of the MP joint before operation is 34.59±5.32°, it increased 6.29±2.98° and to 40.89±2.36° when the plantar plate were cut, laterthe cut of the bilateral collateral ligaments increased another 9.71±1.94° and to 50.60±2.01°. Both had an increasing trend for the angle of flexion ofthe MP joint (Plt;0.01). The bilateral collateral ligaments had more influence than the plantar plate (Plt;0.01). There was the same effect in different sequence (Pgt;0.05). In 2 cases with plantar section, the flexion angle of MP joint could achieve 15° to 45° in 2 monthes. The other 9 cases with both plantar section and bilateral collateral ligaments cut, the MP joint flexion achieved 10.3° to 58.4° in 26.3 months. Conclusion The flexion angle of the MP joint can be increasedby cutting the bilateral collateral ligaments and the plantar plate.