Objective:To assess the operation and usage conditions of all water improvement projects in Qingdao, master the water fluoride content and the prevalence of dental fluorosis in children in drinking-water-borne endemic fluorosis villages, evaluate the prevention and control effect of water improvement project.Methods:From April to October in 2020, all drinking-water-borne endemic fluorosis villages in 7 cities (districts) of Qingdao were selected to investigate the operation and usage conditions of water improvement project, water fluoride and prevalence of dental fluorosis of 8 to 12 years old children. The prevention and control effect of water improvement project on drinking-water-borne endemic fluorosis in Qingdao was evaluated according to the control contents and criteria of drinking-water-borne endemic fluorosis.Results:There were 1 146 drinking-water-borne endemic fluorosis villages, the water improved rate of villages was 100.00% (1 146/1 146), the rate of normal operation of water improvement project was 99.91% (1 145/1 146). There were 1 130 villages with qualified water fluoride and the qualified rate was 98.60% (1 130/1 146). A total of 23 473 children aged 8 - 12 years old were examined, and 631 children were detected with dental fluorosis. The detection rate of dental fluorosis was 2.69% (631/23 473), the dental fluorosis index was 0.048, and the prevalence was negative. The detection rate of dental fluorosis of children in villages with excessive water fluoride (7.03%, 40/569) was higher than that in villages with qualified water fluoride (2.58%, 591/22 904, χ 2 = 41.235, P < 0.01). Conclusion:The operation and usage conditions of water improvement projects in 7 drinking- water-borne endemic fluorosis cities (districts) in Qingdao are good, and the detection rate of dental fluorosis in children is low, which has reached the national control standard.