Objective To explore the effect of external application of traditional Chinese medicine mask with plaster mask combined with tranexamic acid and hydroquinone cream on skin barrier function in patients with melasma. Methods A total of 70 patients with melasma admitted to our hospital from January 2023 to January 2025 were selected, and they were divided into the control group and the observation group according to different treatment plans, with 35 patients in each group. The control group was treated with tranexamic acid solution wet compress combined with hydroquinone cream external application, and the observation group was treated with external application of traditional Chinese medicine mask with plaster mask on the basis of the control group. The Melasma Area and Severity Index (MASI) score, skin barrier function, skin color uniformity parameters and skin physiological indicators were compared between the two groups. Results The MASI score of the observation group after treatment [(8.42±2.15)points] was lower than that of the control group [(12.86±2.73)points] (P<0.05). The TEWL and SCH of the observation group after treatment were better than those of the control group (P<0.05). The L value of the observation group after treatment was higher than that of the control group, and the b value and a value were lower than those of the control group (P<0.05). The SC and R2 of the observation group after treatment were higher than those of the control group, and the skin pH value was lower than that of the control group (P<0.05). Conclusion External application of traditional Chinese medicine mask with plaster mask combined with tranexamic acid and hydroquinone cream can effectively improve the skin barrier function of patients with melasma, enhance skin color uniformity, reduce the severity of melasma, and optimize skin physiological state.