Objective To analyze the characteristics of self-harm behavior among adolescents aged 11 to 18 on the psychological support hotline and factors influencing medical treatment after self-harm. Methods From January 1， 2020 to December 31， 2022， adolescents reporting history of self-harm who called the Beijing Psychological Support Hotline were selected as the research subject. The operator asked the caller about the method， cause， purpose of self-harm， and whether to seek medical advice during the last self-harm behavior before the call， and compared the self-harm behavior characteristics of adolescent callers of different genders and age groups. Logistic regression was used to analyze the factors related to seeking medical advice after self-harm. Results A total of 6 022 adolescent callers were included， of which 77.9% （4 690/ 6 022） were female and 53.8% （3 241/6 022） were aged 11 to 15. The most common way of self-harm was to cut with a knife， accounting for 55.3% （3 328/6 022）. The top two causes of self-harm were depression and family conflicts， accounting for 32.2% （1 940/6 022） and 31.7% （1 908/6 022）， respectively. Eighty-five percent （5 116/6 022） of callers had severe suicidal ideation when self-injuring， and only 25.2% （1 519/6 022） of callers sought medical advice after self-injuring. Compared with male adolescent caller， female caller had a higher proportion of self-harm caused by cutting with a knife， stronger suicidal ideation， but a lower rate of seeking medical advice after self-harm， and the differences were statistically significant （χ2 =71.534， 9.311， 14.882； P ＜ 0.05）. The proportion of caller aged 16 to 18 taking therapeutic drugs was higher than that of caller aged 11 to 15， and the difference was statistically significant （χ2 =67.485， P＜0.001）. Multivariate Logistic regression analysis showed that males ［OR=1.199， 95%CI （1.022， 1.406）］， 16 to 18 years old ［OR=1.261， 95%CI （1.058， 1.504）］， middle ［OR=1.388，95%CI (1.131，1.705）］ or high school ［OR=1.371，95%CI（1.056，1.780）］ education， taking therapeutic drugs ［OR=3.341， 95%CI （2.861， 3.900）］ or other toxic substances ［OR=3.669， 95%CI （2.674， 5.034）］， and severe suicidal ideation ［OR=3.913， 95%CI （1.969， 7.776）］ were risk factors for adolescent caller seeking medical advice after self-harm， and the differences were statistically significant （P＜ 0.05）. self-harm frequency ≥ 2 times ［OR=0.749， 95%CI （0.648， 0.865）］ and self-harm caused by learning problems ［OR=0.584， 95%CI （0.404， 0.844）］ were protective factors for adolescent caller seeking medical advice after self-harm， and the differences were statistically significant （P＜ 0.01）. Conclusions Adolescent hotline callers often engage in self-harm behavior through knife cuts， and the suicidal ideation is severe when the behavior occurs， but they rarely seek medical advice. There are differences in self-harm characteristics among adolescent callers of different genders and age groups. Gender， age， mode of self-harm， reason for self-harm， number of self-harm， and intensity of suicidal ideation at the time of self-harm were all influential factors in adolescent callers seeking medical care after self-harm.