Objective To explore the mechanism of laser and photodynamic therapy (PDT) of hemangioma. Methods A total of 48 6-month-old male chickens were divided into 6 groups, with 8 in each group. The side with the untreated comb served as the control. Group A was the control group. In groups B and C, the combs received laser irradiation once of 10 J/cm2 and 15 J/cm2, respectively, for 2-3 minutes. In group D, hematoporphyrin monomethyl ether (HMME) of 10 mg/kg was injected into the left-side axillary vein once. In groups E and F, the combs received laser irradiation of 10 J/cm2 and 15 J/cm2, respectively, after 10 mg/kg HMME was injected for 10 minutes into the left-side axillary vein. On the 14th day, HE staining was performed and the decrease rate of the number of capillary vessels was calculated. Besides, TUNEL stainingwas conducted to observe the condition of capillary endothel ium apoptosis. Results No animal died after the operation,the combs in groups A and D had no obvious changes in shape and color, but the ones in the other groups had leukasmus, edema, necrosis and dark crust. According to histological observation, in groups A and D, the combs had no obvious changes. But in the other groups, tissue exudation, edema, inflammatory cell exudation, decreasing number of vessels, waning vascular cal iber, thrombus, and partial capillary endothel ium apoptosis were found. The decrease rate of the number of capillary vessels was as follows: 7.87% ± 2.50% in group A, 48.58% ± 5.10% in group B, 57.58% ± 8.17% in group C, 8.84% ± 3.13% in group D, 61.26% ± 16.87% in group E and 68.56% ± 10.54% in group F. The apoptosis index in all groups was 1.05 ± 0.76, 82.22 ± 6.18, 94.13 ± 1.64, 1.38 ± 0.52, 101.88 ± 5.94, 104.88 ± 6.22, respectively. There were significant differences between groups B, C, E, F and groups A, D in the above two items (P lt; 0.01). There were significant differences between groups B and E as well as between groups C and F (P lt; 0.01). There were no significant differences between groups B and C as well as groups E and F (P gt; 0.05). Conclusion Apoptosis of capillary endothel ium maybe play an important role in the laser and photodynamic therapy of hemangioma apart from the direct effect of laser.