Abstract: Objective To understand the prevalence of fluorosis through water drinking and evaluate the effects of the prevention project by reducing fluorine in water in Dingxiang county. Methods The fluorine in water was detected by detection methods of fluorine in water in endemic fluorosis area(WS/T 106), the fluorine in urine was detected by ion selective electrode method(WS/T 89), the dental fluorosis was diagnosed by Dean's method(tooth defect was recorded)and the clinical fluorosis of bone was diagnosed according to diagnosing and grading standard of endemic fluorosis of bone(WS 192-2007)specified in the technical protocol of prevention and treatment of endemic fluorosis through water drinking. Results The content of fluorine in water in 3 surveillance areas exceeded limit; The detection rate of dental fluorosis was 60.7%, the detection rate of defective dental fluorosis was 12.1% and the dental fluorosis index was 1.23 in children aged 8-12 years, The median of urine fluorine value in children was 5.66 mg/L(ranged from 3.11 mg/L to 12.4 mg/L)and the standard deviation was 1.94 mg/L. The median of urine fluorine value in adults was 7.31 mg/L(ranged from 4.07 mg/L to 19.5 mg/L)and the standard deviation was 2.41 mg/L The detection rate of clinical fluorosis of bone in adults was 8.9%. Conclusion The surveillance indicated that the overall prevalence of fluorosis had declined in 3 surveillance areas, but the content of fluorine in water, the detection rate of dental fluorosis and urine fluorine value in children were still high. It is necessary to improve the quality of the water quality improvement project to reduce fluorine content to reduce the prevalence of endemic fluorosis.