Objective：This study aims to evaluate effects and mechanisms of laparoscopic sleeve gastrectomy（LSG）on the changes of sex hormone level in obese young men with acanthosis nigricans. Methods：The clinical data of 45 young male obesity patients［body mass index（BMI）≥30 kg/m2］who underwent LSG was collected. The obesity patients were divided into obesity without acanthosis nigricans group（OB group，n=23）and obesity with acanthosis nigricans group（AN group，n=22）. The anthropometries parameters（weight，BMI，waist circumference，and body fat percentage），glucose metabolic indices［plasma glucose，glycosylated hemoglobin（HbAlc），insulin，homeostasis model assessment-insulin resistance index（HOMA-IR）］，lipid profiles（total cholesterol，triglyceride，high density lipoprotein cholesterol，low density lipoprotein cholesterol），inflammatory factors（serum uric acid，interleukin-6，tumor necrosis factor α） and sexual hormones were evaluated and calculated. Changes of these variables before and after surgery were analyzed. Results：LSG can significantly improve the level of total testosterone（TT）in obese young men. Before operation，the TT of AN group was only（7.60 ± 4.43）nmol/L，which was lower than the normal level and significantly lower than that of OB group（P < 0.01）. TT of OB group was（10.42 ± 5.14）nmol/L，which was also lower than the normal level. At 6 months after operation，TT levels in OB group and AN group were significantly higher than those before operation（P < 0.05），TT level in OB group was（15.58 ± 5.32）nmol/L，was（21.13 ± 23.43）nmol/L in AN group，and TT level in AN group increased more significantly than that in OB group（P < 0.05）. At 6 months after operation，inflammatory factors，plasma insulin level and HOMA-IR decreased significantly in OB group and AN group（P < 0.05），especially in AN group. TT was negatively correlated with BMI，body fat ratio，HOMA-IR，fasting and 2 hours postprandial insulin（P < 0.05），but not with fasting and 2 hours postprandial blood glucose（P > 0.05）. Conclusion：LSG can not only effectively reduce the weight of obese patients，but also significantly alleviate the hypotestosterone of obese men with acanthosis nigricans by improving insulin resistance and inflammation.