Objective:To detect serum levels of vitamin A (Vit A), vitamin D(Vit D)25-hydroxy vitamin D[25-(OH)D] and vitamin E(Vit E) in children aged 0-6 years in Tibetan Plateau of Garzi Prefecture, thus providing references for physical examinations and prevention of 4 key diseases (rickets, malnutrition anemia, pneumonia and diarrhea) in children in plateau areas by relevant government departments.Methods:A total of 2 122 children who participated in physical examination in 12 townships of Xiangcheng County and 14 townships of Daocheng County, Garzi Tibetan Autonomous Prefecture, Sichuan Province from April 2017 to April 2019 with 0-6 years old were recruited for surveying physical measurements and collection of venous blood.Serum Vit A and Vit E levels were detected by high performance liquid chromatography.Serum levels of 25-(OH)D were detected by high performance liquid chromatography tandem mass spectrometry.The relationship between Vit A, Vit E and 25-(OH)D levels with the gender, age, seasonal change and altitude was analyzed.Results:The serum Vit A level, subclinical Vit A deficiency rate and marginal vitamin A deficiency rate were(1.05±0.27) μmol/L, 8.15%(173/2 122 cases) and 45.99%(976/2 122 cases), respectively in 2 122 children with 0-6 years old.There were significant differences in the serum Vit A level, the subclinical Vit A deficiency rate and the marginal vitamin A deficiency rate in children with different ages, seasons and altitudes (all P<0.05). The serum level of 25-(OH)D and 25-(OH)D deficiency rate insufficient rate were (24.65±6.45) ng/L, 6.03%(128/2 122 cases) and 16.59%(352/2 122 cases), respectively.There were significant differences in the serum level of 25-(OH)D, 25-(OH)D deficiency rate and 25-(OH)D insufficient rate in children with different ages and seasons (all P<0.05). The mean serum Vit E level, Vit E deficiency rate and Vit E insufficient rate were (7.81±1.74) mg/L, 2.78%(59/2 122 cases) and 29.59%(628/2 122 cases), respectively.There were significant differences in serum Vit E level, Vit E deficiency rate and Vit E insufficient rate in children with different ages and seasons (all P<0.05). The mean serum levels of Vit A and Vit D remained the lowest before the age of 1 year, and their deficiencies at this age were the most significant.The mean serum level of Vit E remained the lowest in >1-2 years old, and its deficiency and insufficient at this age were the most significant.Vit A, D and E levels were significantly affected by seasonal changes, which were significantly higher in the summer than in the spring, autumn and winter.In addition, Vit A and 25-(OH)D were significantly affected by the altitude, which were the lowest above 4 km altitude. Conclusions:The overall serum levels of Vit A, 25-(OH) D and E in children with 0-6 years old in Tibetan Plateau areas of Ganzi Prefecture are lower than those in plain areas.Vit A, 25-(OH) D and Vit E levels significantly differed in the age, season and altitude, which are related to the lack of local resources, insufficient maternal nutrition during pregnancy and insufficient intake after birth, as well as temperature and light caused by changes in local seasons and altitude.Therefore, it is necessary to make reasonable supplements during pregnancy to prevent vitamin deficiency.