Objective To investigate the effect of tranilast on wound healing and the mechanism of inhibiting scar hyperplasia in mice, and to study the relationship between the inhibiting ability of tranilast on scar hyperplasia and administration time. Methods Sixty-six Kunming mice were selected to build deep II degree burn model, and were randomly divided into the control group (18 mice), the early intervention group (18 mice), the medium intervention group (18 mice), and the late intervention group (12 mice). The mice in the early intervention group, the medium-term intervention group, and the late intervention group were given tranilast 200 mg/(kg·d) by gastrogavage at immediate, 7 days, and 14 days after burn respectively, and the mice in the control group were managed with same amount of normal saline every day. The wound healing was observed regularly. At 14, 28, and 42 days in the early and medium intervention groups and at 28 and 42 days in the late intervention group, fresh tissues were taken from 6 mice to observe the shape of mast cells by toluidine blue staining, collagen content by Masson staining; the collagen type I and collagen type III content were measured to calculate the I/III collagen content ratio by immunohistochemistry method, the contents of transforming growth factor β1 (TGF-β1) and histamine were detected by ELISA; and the ultrastructure of fibroblasts was observed under transmission electron microscope. Results There was no significant difference in wound healing time between groups (F=1.105,P=0.371). The mast cells number, collagen content, TGF-β1 content, histamine content, and the I/III collagen content ratio in the early intervention group were significantly less than those in the other groups (P<0.05). Significant difference was found in mast cells number, collagen content, and histamine content between control group and medium or late intervention group at the other time points (P<0.05) except between control group and late intervention group at 42 days (P>0.05). Compared with the control group, the activity of fibroblasts in the early intervention group was obviously inhibited, and the arrangement of the fibers was more regular; the fibroblast activity in the medium and late intervention groups was also inhibited obviously. Conclusion Tranilast has no obvious effect on the wound healing time in mice. Tranilast intervention shows the inhibitory effect on the scar hyperplasia which can significantly reduce the number of mast cells, the content of histamine and TGF-β1, inhibit the ability of fibroblasts synthetic collagen and adjust the proportion of collagen synthesis. The immediate tranilast intervention may have the best inhibitory effect on scar hyperplasia.