Abstract:  The experiment was conducted to study the effects of different Ca levels on functional injury of kidneys induced by fluoride in rat and provide the theory basis for the selection of calcium dose for treating fluorosis patients. Fifty health Wistar rats at the age of 21 days were chose and randomly divided into 5 groups: control group, high F group (including 150 mg·kg^-1 F^-), high F and low Ca group (including 150 mg·kg^-1 F^-and 2％ CaCO₃ ), high F and middle Ca group (including 150 mg·kg^-1 F^-and 3％ CaCO₃), high F and high Ca group (including 150 mg·kg^-1 F^- and 4％ CaCO₃). After 60 days, blood was taken to measure the content of calcium (Ca), phosphate (P), blood urea nitrogen (BUN), serum creatinine (SCr) in the serum. The kidneys were weighted to calculate viscera index. And the enzymatic changes including lactate dehydrogenase (LDH), succinic dehydrogenase (SDH) and alkaline phosphatase (ALP) were detected. Immunohistochemistry methods were employed to determine the expression of CD₁₁ and TNF-α protein in kidney of male rats. The result showed that, compared to control group, the weight of high F group was decreased significantly (P<0.01); its P in serum was much higher than normal group (P<0.05); the content of LDH, SDH and ALP of high F group were successively increased (P<0.01); CD₁₁ and TNF-α protein expression was markedly higher (P<0.01). Compared with the high fluoride group, high F and low Ca group and high F and middle Ca group increased body weight obviously (P<0.05); the levels of Ca and P in serum and LDH, SDH and ALP in kidney were significantly decreased; expression levels of CD₁₁ and TNF-α in high F and low Ca group were significantly inhibited (P<0.01). Between results of high F and high Ca group and high F group, there was no significant difference (P>0.05) in viscera index and the amounts of LDH, ALP and SDH, the BUN and SCr levels was impermissibly high (P<0.05), and the expression levels of CD₁₁ and TNF-α didn’t show significant changes (P>0.05). The results suggested that fluorine in high doses may cause the functional injury of rat kidney. Calcium in both low and middle doses could reduce the toxic effects of kidney caused by fluorine and have the protective role in kidney tissue. The excessive calcium, instead of alleviating the toxic effects of fluorine on kidney, may make the kidney damage more serious.