To investigate and compare the biological effect of proliferation,enzyme activity and growth factor after double wavelength low level laser therapy (LLLT) on human embryonic skin fibroblasts (CCC-ESF) in vito,and explore the molecular mechanism of wound healing,in vitro culture of CCC-ESF is divided into control group and experimental groups (635 nm group,808 nm group,635 nm/808 nm group),laser of 20 mW/cm2,12 J/cm2 is applied to detect cell proliferation,reactive oxygen species (ROS) production,antioxidant enzyme activity [catalase (CAT)and superoxide dismutase (SOD)],lipid oxidation (MDA) and amount of cytokines related.Cell proliferation rate in the 635 nm group is significantly higher than that in other groups;ROS levels are 14.55%,7.49% and 14.92% respectively in 635 nm,808 nm and 635 nm/808 nm groups,which are higher than that in the control group;CAT and SOD enzyme activity increases after LLLT;808 nm laser promotes the level of MDA and expression of interleukine-1 (IL-1) and fibroblast growth factor (FGF);808 nm laser can stimulate the secretion of insulin-like growth factor 1 (IGF-1) and glial cell line-derived neurotrophic factor (GDNF).Low levels of oxidative stress induced by LLLT can promote the proliferation of CCC-ESF,improve cell viability,and enhance cellular resistance to the external environment.LLLT stimulates the secretion of a variety of cytokines and regulates the wound healing process.Biological effect produced by double wavelength LLLT is better than that with a single wavelength in CCC-ESF.