Objective: To explore the changes in liver function of Tibetan youth living in plateau with different body mass index (BMI) during the early stage of migration to the plain, and to provide scientific basis for high attitude de adaptation. Methods: A total of 3 035 Tibetan youth who firstly migrated to the plain (Shaanxi) from the plateau (Tibet) were selected as the research subjects, and were screened for symptoms of plateau de adaptation. Participants were divided into four groups: underweight, normal weight, overweight and obese, and received liver function test on the 3rd, 6th, 9th dayafter migration, respectively. Chi square test was used to detect the abnormal rate of liver function indicators among each group, and binary Logistic regression analysis was used to explore the relationship between BMI and abnormal liver function indicators. Results: The alanine aminotransferase(ALT), Aspartate aminotransferase(AST), γ glutamyl transpeptidase (GGT) of overweight Tibetan male and obese Tibetan male and female adolescents, the total bile acid (TBA) of overweight Tibetan male and obese Tibetan female were higher than those of the normal weight group at the early stage of de adaptation( P <0.05). With the de adaptation for 3, 6, 9 days, the indexes showed an overall upward trend, including: direct bilirubin (DBIL) in overweight male and female adolescents, total protein (TP) and globulose (GLOB) in obese female adolescents( P <0.05). The abnormal rate of overweight group (male ALT: 13.9%), obesity group (male and female ALT, GGT: 34.3%, 26.7%, 11.4%, 13.3%; female AST:10.0%) was significantly higher than that in underweight (2.8%, 3.5%, 0, 1.0%, 1.5%) and normal group(3.5%, 3.4%, 0.9%, 3.6%, 4.1%)( χ 2=48.07, 20.55, 20.55, 17.93, 10.23 , P <0.05). Binary Logistic regression analysis showed that after adjusting for age and gender, overweight was positively correlated with abnormal ALT( OR=2.10, 95%CI =1.20-3.62). Obesity was positively correlated with abnormal ALT( OR=5.50, 95%CI =4.23-7.40) and GGT( OR=4.10, 95%CI =2.03-6.74)( P <0.05). Conclusion During the early stage of migration to the plain among Tibetan youth living on the plateau, changes in liver function indicators are related to BMI. Overweight and obese Tibetans have a higher abnormal rate of liver damage indicators. It is suggested that individuals with high risk of obesity should undergo health examination and medical supervision when migrates from plateau to plain.