Objective To study the correlation of serum vitamin D [25(OH)D] levels with the severity of childhood atopic dermatitis (AD). Methods　A total of 152 children with AD were enrolled. The severity of AD was assessed by SCORAD. Serum 25(OH)D levels were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS). The correlation between the severity of AD and serum 25 (OH) D levels was analyzed. Results　In the 152 children (81 males, 71 females) with AD, the median age was 3.5 years. There were 51 cases of mild AD (33.6%), 80 cases of moderate AD (52.6%), and 19 cases of severe AD (12.5%). Vitamin D was sufficient in 55 cases (36.2%), insufficient in 65 cases (42.8%), and deficient in 32 cases (21.1%). The SCORAD score in children with AD was not correlated with serum 25 (OH) D levels (r=?0.047, P=0.567), while positively correlated with total serum IgE (r=0.244, P=0.003) and the percentage of blood eosinophils (r=0.239, P=0.004). Conclusions　Serum vitamin D insufficiency and deficiency were more common in AD children, but the severity of AD was not significantly correlated with serum 25 (OH) D levels.