In this experiment, 32 goats were performed osteotomy limb lengthening by tibial upper metaphyseal. The strength, stiffness and energy absorption of the lengthened bone had been measured in different period after the lengthening ceased. The results demonstrated that during the lengthened bone healing process, the recovery of bone mechanical properties is compatible with its histological changes; and the healing process of lengthened bone can be roughly divided into three biomechanical stages: (1) Low strength and low stiffness stage; (2) Low strength and high stiffness stage; (3) High strength and high stiffness stage.