Objective To summarize the clinical characteristics of adolescent acne patients and analyze the related influencing factors of post-acne scar formation in adolescence. Methods A total of 200 acne patients aged 10-19 years who visited the Department of Dermatology, Heshan Hospital of Chinese Medicine from April 2024 to April 2025 were selected as the research subjects. Data on clinical characteristics of acne (rash type, severity, distribution site), diet and exercise habits were collected through cross-sectional survey, and the incidence and related factors of acne scar (depressed, hypertrophic) were analyzed. Results Among the 200 patients, acne was most common on the cheeks (92.00%) and forehead (71.00%), mainly mixed rashes (93.00% with comedones, 92.00% with papules), and grade Ⅲ acne was the most common (54.00%). The incidence of scar was 36.00% (61 patients with depressed scar, 11 patients with hypertrophic scar). Multivariate analysis showed that acne severity of grade Ⅲ-Ⅳ, frequency of sweet food intake ≥3 times/week, irregular exercise, high psychological stress and frequent staying up late were the main risk factors for depressed scar formation (P <0.05), and family history of post-acne scar and habit of squeezing acne were the main risk factors for hypertrophic scar formation (P <0.05). Conclusion Post-adolescent acne scars are mainly depressed, and their formation is closely related to acne severity, high-sugar diet, insufficient exercise, psychological stress and sleep behavior. Hypertrophic scar is related to heredity and mechanical stimulation. Therefore, early intervention on controllable factors for high-risk groups should be carried out to reduce the risk of post-acne scar.