Objective To explore the clinical effect of negative pressure suction combined with washing by Chinese herbal bath to treat small penis in obese children at school age.Methods The data of 60 obese cases with small penis at the First Affiliated Hospital of Xinxiang Medical University from June 2016 to September 2017 were retrospectively analyzed,the age ranged from 7 to 15 years old,and the average age was (11.1 ± 2.0) years old,the body mass index(BMI) was 19.2-30.5,and the average BMI was 24.5 ± 2.6.Treatment group received the penis treatment with negative pressure instrument suction supplemented by traditional Chinese medicine bath treatment,once a day,20 minutes each times,10 days asa course,a totally of 2 treatment courses.Other 46 cases of male children who came to our hospital in the same period for physical exam were selected as healthy control group,aged 8-14 years old [(11.2 ± 2.1) years],BMI:14.6-21.0,mean 18.1 ± 1.6,and the relaxation length and elongation of 20 days before and after the normal growth state of the penis in the control group were measured.The length and elongation of the penis in the treatment group were compared with those of the healthy control group before and after treatment.Results The length of penile relaxation in the treatment group increased to (3.76 ±0.61) cm in comparison with that before treatment (2.94 ± 0.52) cm,and the difference was statistically significant (t =-7.82,P ＜ 0.05);the penis elongation increased compared with that before treatment (4.29 ± 0.67) cm to (5.37 ± 0.82) cm,and the difference was statistically significant (t =-7.91,P ＜ 0.05).The initial relaxation length of the control group was (3.96 ± 0.65) cm,(4.07 ± 0.65) cm 20 days after natural growth,the difference was not statistically significant (t =-0.82,P ＞ 0.05),the initial stretch length was (5.96 ± 0.92) cm,(6.03 ± 0.90) cm natural growth after 20 days,and the difference was not statistically significant (t =-0.37,P ＞ 0.05).Before and after treatment,the length of penis relaxation and elongation were significantly increased,but they didn't reach the normal level at the same age.Conclusions Negative pressure suction supplemented with Chinese herbal medicine bath has a significant effect on treating obese children with small penis.