Objective To analyze serum 25-dihydroxy vitamin D[25(OH)D] levels of children in high altitude area in summer and to enrich serum 25(OH)D database resources,to explore the ideal serum 25(OH)D levels for children in China. Methods Each child was selected to collect venous blood in August and September 2013.The subjects were 0.2~7.3 years old children lived in Zhongzhuang,Huangzhong and Guide in Qinghai county.Total was 230 case,mean of age was (4.3±1.9) years old,boys were 113,girls were 117.The serum 25(OH)D levels were assayed by ELISA. Results 1)The mean serum 25(OH)D levels in boys and girls were (57.31±16.47)nmol/L and (53.48±14.39)nmol/L,respectively,there was no significant difference(P>0.05).The mean serum 25(OH)D levels in infant and preschool were (58.08±19.17)nmol/L and (54.15±13.50)nmol/L,respectively.There was no significant difference(P>0.05).There was no relation between serum 25(OH)D levels and age (r=-0.093,P>0.05).2)The mean serum 25(OH)D levels in Zhongzhuang,Huangzhong and Guide were (49.74±13.72)nmol/L,(52.59±15.07n)mol/L and (61.54±15.10)nmol/L,respectively.The mean 25(OH)D level of Guide was higher than Zhongzhuang and Huangzhong with significant difference.There was no significant difference between Zhongzhuang and Huangzhong.3)It was no discrepancy in the orders of the serum 25(OH)D levels and the altitude.It was observed that the serum 25(OH)D level was increased by decreased latitude.The percentage of serum 25(OH)D levels less than 27.5nmol/L of children was 2.1%(5/230). Conclusions There is significant difference in altitude area in summer.Altitude and latitude could have influence on the serum 25(OH)D.Gender and age have no influence on the serum 25(OH)D.Most of children on 25(OH)D levels in Qinghai are higher than 27.5 nmol/L.