Abstract: Objective To establish an animal model of drinking-water endemic fluorosis and to observe the changes of serum biochemical parameters.Methods A total of 48 Wistar rats were randomly divided into four groups,including control group(distilled water),low-dose group(NaF,50 mg/L),medium-dose group(NaF,100 mg/L),and high-dose group(NaF,150 mg/L)(12 rats in each group).After eight weeks,the rats were sacrificed by anesthesia and their serum samples were collected.The biochemical techniques were used to test serum calcium,phosphorus,uric acid,and activity of alkaline phosphatase(ALP)in serum of fluorosis rats.Changes in the fluorine content in serum and bone of the rats in each group were analyzed with fluoride ion selective electrode method.Results The fluorine content in serum (0.175±0.025,0.230±0.036,and 0.313±0.042 μg/mL)and bone(893.628±67.748,1001.111±34.121,and 1248.152±77.131μg/mg) and the level of phosphorus in serum(2.434±0.778,2.478±0.246,and 2.505±0.365 mmol/L)for low-,moderate-,and high-fluoride group were significantly higher than those of the control group(all P<0.05) and increased with the increment of fluoride concentration.The level of calcium in serum (2.212±0.282,2.185±0.300,and 2.148±0.179 mmol/L)in the low-,moderate-,and high-fluoride group were significantly lower than that of the control group(P<0.05).The level of uric acid in serum in high-dose group(47.286±1.732 μmol/L)was significantly lower than that of the control group,and the activity of ALP in high-dose group(92.667±11.719 U/L) increased significantly.Conclusion Serum calcium,phosphorus,fluorine,uric acid and alkaline phosphatase are important indicators in auxiliary diagnosis of endemic fluorosis and could be used as early diagnosis parameters before bone morphological changes.