Objective To accurately control the intensity and area of burns by using fractional carbon dioxide laser， and to explore the optimal energy intensity to prepare a model of deep second-degree skin burns. Methods Firstly， two groups ofburn models with different energy intensities were obtained by using 50 mJ and 80 mJ CO2 fractional lasers， and the skinchanges on the surface of the burn site were observed after burn modeling， and photographs were taken at 0，3，7 and 14 daysafter modeling to observe the healing of burns and analyze the wound healing rate. Subsequently， HE staining， Massonstaining， Col Ⅰ and Col Ⅲ immunohistochemical staining were performed on the burn tissues taken at different time points，and the results were analyzed. Results Histological staining of the materials at different time points showed that there weresignificant differences in the depth of laser perforation， hair follicle regeneration and scar formation between the two groups.The immunohistochemical staining results of Col Ⅰ and Col Ⅲ showed that there were also significant differences in collagen regeneration between the two groups. Comprehensive analysis showed that the damage caused by 80 mJ energy intensity to the skin tissue of mice was more consistent with the characteristics of the deep second-degree burn model. Conclusion In this study， a model of deep second-degree burns with obvious obstacles in skin tissue regeneration was successfully constructed on the back of mice by carbon dioxide fractional laser， and the degree of damage was evaluated in detail by histology， immunohistochemistry， etc.， and finally the energy intensity of 80 mJ was screened for the construction of a deep second degree burn model， which is expected to provide a new and favorable tool for studying the pathophysiology of burns and the screening of drugs for skin tissue regeneration.

Deep second-degree burn model, Carbon dioxide fractional laser, Skin injury