Based on Newton's laws of motion, equilibrium conditions of plane force system and ankle joint structural features, a force analysis was made of ankle joint when people leaning forward and standing on one leg and lifted lead with overweight and weightlessness. The results showed that force on the talus when people leaning forward and standing on one leg with overweight is 1.5 times of that in equilibrium and force on the talus when people standing on lifted lead with overweight is 1.3 times of that in equilibrium. The force on the talus in the above two conditions will increase with the increa...