Objective To explore the effect of fire needle combined with red and blue light therapy on skin lesion severity in patients with moderate-to-severe acne. Methods A total of 86 patients with moderate-to-severe acne diagnosed and treated in the Department of Dermatology, Danyang Maternal and Child Health Hospital from January 2023 to April 2025 were selected, and they were divided into the control group and the observation group according to different treatment plans, with 43 patients in each group. The control group received red and blue light therapy, and the observation group received fire needle combined with red and blue light therapy. The clinical efficacy, skin lesion severity, skin physiological indicators and inflammatory factor levels were compared between the two groups. Results The total effective rate of the observation group (95.35%) was higher than that of the control group (79.07%) (P <0.05).The scores of skin lesion type, quantity, color, swelling and pain in the observation group after treatment were lower than those in the control group (P <0.05).The erythema index of the observation group after treatment was lower than that of the control group, and the skin elasticity and skin water content were higher than those of the control group (P <0.05). The levels of IL-1, IL-4 and IL-6 in the observation group after treatment were lower than those in the control group (P <0.05). Conclusion Fire needle combined with red and blue light therapy has a definite effect in the treatment of moderate-to-severe acne. It can not only reduce skin lesions, improve skin erythema, elasticity and water content, but also reduce the levels of inflammatory factors.