This paper investigates the fatigue fracture of tibia that often occurs in soldiers, as well as in dancers and athletes. The data of ground reaction force(GRF) of soldiers were measured using a force platform in three common gaits, the marching, parading and running. The stress distribution in tibia under these GRF's were analyzed with a FE model. Then the fatigue life of fresh human tibia specimens were tested under the corresponding maximum stress by compressive fatigue test.Results show that the GRF is the smallest in quick marching, the next in parade step and the largest in running. e. g. the maximum vertical force are 1391. 6N、1156. 4N and 744. 8N in running,parading, and marching steps, respectively. The stress distribution under the GRF is not uniform in the tibia. The maximum stresses occur at the position 1/3 tibia length from the upper end,where the tibia fracture often ocurs in clinic. The maximum stresses are 110MPa and 115MPa in the parade step and running respectively. The fatigue lifes of tibia specimens are 793, 927,2467 and 13425 under the compressive stress of 100MPa, 90MPa, 70MPa and 50MPa, respectively. This means that the fracture in tibia are mostly like stress fractures, the larger the stress, the higher the incidence of stress fracture.