Objective:To explore the levels of vitamin A(VA) and vitamin D(VD) in blood of children with tic disorder (Tic disorder, TD) and their associations with tic symptoms severity and clinical types, so as to provide evidence for better prevention and treatment of TD.Methods:A total of 245 children with TD from September 2018 to April 2019 in the department of child Health care, affiliated hospital of qingdao university were enrolled as the case group and 63 healthy children who underwent routine physical examination at the same time as the control group. The levels of VA and VD were measured and their relationship with the severity of tic symptoms and clinical types were analyzed.Results:(1)The VD level of the case group was significantly lower than that of the control group ((23.72±8.87) μg/L , (26.61±7.59) μg/L, t=-2.24, P=0.03), and the proportion of insufficiency or even lack (37.31%, 75/201) was higher than the control group (15.79%, 9/57) (χ 2=9.37, P=0.002). (2)According to the Yale global tic severity scale(YGTSS), the children in the case group were divided into mild TD group, and moderate-to-severe TD group. ①There were significant differences in serum VA and VD levels in mild TD group, moderate-to-severe TD group and the control group ( F=29.79, P<0.01; F=10.90, P<0.01). Among them, the content of VA and VD in moderate-to-severe TD group were lower than those in mild TD group and control group (VA: (0.29±0.06)mg/L, (0.35±0.06)mg/L, (0.34±0.06)mg/L; VD: (21.01±8.30)μg/L, (25.84±8.76)μg/L, (26.61±7.59)μg/L). ②VA and VD levels of children with TD were negatively correlated with the severity of symptoms ( r=-0.325; P<0.01; r=-0.228; P=0.001). (3)According to DSM-V classification criteria, TD children were divided into PTD group, CTD group and TS group. ①There was no significant difference in serum VA level among different clinical types of TD children ( F=0.87, P=0.46). ②The levels of serum VD were different among the four groups ( F=4.13, P=0.007). Among them, the VD level in TS group was the lowest, and its content was significantly lower than that in control group ((21.83±7.60)μg/L, (26.61±7.59)μg/L, P<0.05)). The prevalence of insufficient or even lack of serum VD in children with different subtypes of TD was higher than that in the control group (χ 2=10.88, P=0.01). Conclusion:Vitamin D deficiency exists in children with TD. The level of vitamin A and vitamin D in serum of children with TD is related with the severity of tic symptoms.The VD level is related with clinical type of TD.