Objective To explore the effect of mucle force on contact force, peak pressure and contact area of foot joint in in vitro biomechanical experiment of foot and ankle, so as to provide references for choosing appropriate loading modes. Methods In neutral position of the ankle joint, fresh calf and foot specimens were simulated with or without mucle force loading. The contact force, peak pressure and contact area of the 1st metatarsophalangeal joint, the 2nd metatarsophalangeal joint, the 1st tarsometatarsal joint, the 2nd tarsometatarsal joint, the medial cuneonavicular joint, the intermediate cuneonavicular joint, the talonavicular joint, the calcicocuboid joint, the subtalar joint ( posterior articular surface) and the tibiotalar joint of normal foot under loading were measured, the results are compared and analyzed. Results Under muscle force loading, the contact force of the 1st metatarsophalangeal joint, the 2nd metatarsophalangeal joint, the 1st tarsometatarsal joint,the 2nd tarsometatarsal joint, the medial cuneonavicular joint, the intermediate cuneonavicular joint, the talonavicular joint and the tibiotalar joint were significantly greater than those without muscle force loading (P<0. 05), and the change percentages were 719. 28% , 311. 37% , 128. 67% , 50. 82% , 54. 89% , 57. 63% ,79. 98% and 50. 34% , respectively. The peak pressures of the 1st metatarsophalangeal joint , the 1st tarsometatarsal joint and the talonavicular joint under muscle force loading were significantly higher than those without muscle force loading ( P < 0. 05), and the change percentages were 176. 14% , 62. 91% and 40. 07% ,respectively. The contact area of the 1st metatarsophalangeal joint, the 1st tarsometatarsal joint, the intermediate cuneonavicular joint and the subtalar joint ( posterior articular surface) under muscle force loading increased significantly (P<0. 05), and the change percentages were 132. 20% , 55. 41% , 30. 97% and 26. 87% , respectively. Conclusions In biomechanical experiment of foot and ankle specimens, muscle force loading has a significant effect on contact force, peak pressure and contact area of each foot joint, especially the forefoot.Therefore, it is necessary to consider the effect of muscle force loading on stress of foot and ankle in the study ofrelated in vitro specimens