We examined immunohistochemical expressions of HSP70 and p-HSP70 in the orthodontic periodontal tissues. In the control group, the HSP70 and p-HSP70 expression was observed in the periodontal ligament fibroblasts and that was kept in low levels. In the experimental group, the strong expression of HSP70 was detected according to over time. However, p-HSP70 expression was a bit delayed. The data suggests that HSP70 has been closely involved in the repair of tissue to maintain homeostasis of the periodontal tissues by the activation of periodontal ligament fibroblasts. Farthermore, the data also suggests that HSP70 act as a molecular chaperone of osteogenesis through an activation of osteoblasts.