To investigate blood vessel remodeling in the process of He-Ne laser irradition on periodontium of experimental tooth movement, a He-Ne laser with weavelength of 632.8 nm and power of 20 mW is used to irradiate the periodontium of experimental tooth movement in rats. Periodontal slice is treated by cyclooxygenase-2 (COX-2) immunohistochemistry dyeing and the results are obtained by image analysis. The results show that the COX-2 expression in periodontium with forced time of 3, 5, 7 d are significantly higher in experimental side than that of control side in the pressure region. While in the tension region, the COX-2 expression in periodontium with forced time of 1, 3, 5, 7 d are significantly higher in experimental side than that of control side. The results indicate that He-Ne laser can increase COX-2 expression in periodontium during the tooth movement in rats, thus probably enhance the vascularization of tooth movement.