Objective To explore the correlation between body mass index and deciduous teeth caries in preschool children. Methods The relevant data of 180 children with dental caries who were treated in the Department of Stomatology, People 's Hospital of Xinjiang Uygur Autonomous Region from January to July 2021 were retrospectively analyzed. The body mass index ( BMI ) value was calculated, the growth and development level and nutritional status were evaluated, and oral examination was performed to analyze the correlation between BMI index and dental caries. Results There was no signifcant diference in the number of decay missing flling tooth and the number of decayed missing or flled surfaces in diferent age groups with diferent BMI standards (P>0.05). Among the children with diferent BMI standards, the number of decay missing flling tooth and the number of decayed missing or flled surfaces in the children with excellent BIM standard were higher than those in the thin and standard, and the diference was statistically signifcant (P<0.05). Conclusion The caries of deciduous teeth in children is closely related to growth and development, and comprehensive measures should be taken as soon as possible to prevent it.