OBJECTIVE To explore the effect of intravascular low level He-Ne laser irradiation on skin flap survival after orthotopic transplantation in avulsion injury. METHODS Fifty eight cases suffered avulsion injury were treated by debridement and orthotopic transplantation of avulsed flap within 6 hours, 31 of them were received intravascular low level He-Ne laser irradiation and routine treatment, and 27 of them were received routine treatment as control group. RESULTS The survival area and quality of avulsed flap in the experimental group were superior to that of control group after 15 days of operation, and the hemorheological items were markedly changed at 5 days after operation. CONCLUSION The better flap survival after orthotopic transplantation in avulsion injury can be improved by intravascular low level He-Ne laser irradiation through changed superoxide dismutase activity and hemorheological items in optimal irradiation intensity.