Objective To investigate the effect of type A botulinum toxin combined with self-crosslinked small molecule hyaluronic acid on the improvement of facial darkness. Methods From September 2023 to May 2024, 80 patients with facial dark complexion admitted to Beauty and Dermatology Department of Xi'an International Port Bohan Medical Beauty Clinic were selected as the research objects. According to different treatment plans, they were divided into control group and study group, with 40 patients in each group. The control group was treated with self-crosslinked small molecule hyaluronic acid, and the study group was treated with type A botulinum toxin+self-crosslinked small molecule hyaluronic acid. The therapeutic effect, facial skin related indicators, aesthetic effect and adverse reactions were compared between the two groups. Results The total improvement rate of the study group was 97.50%, which was higher than 80.00% of the control group, and the difference was statistically significant (P <0.05). After treatment, the scores of elasticity and moisture in the study group were higher than those in the control group, and the scores of melanin and oil were lower than those in the control group, the differences were statistically significant (P<0.05). After treatment, the subjective and objective scores of facial aesthetics in the study group were higher than those in the control group, the differences were statistically significant (P <0.05). There was no significant difference in the incidence of adverse reactions between the two groups (P >0.05). Conclusion The combined application of type A botulinum toxin and self-crosslinked small molecule hyaluronic acid in facial skin color can effectively improve facial skin color and aesthetic effect, with safe curative effect and high application value.