By using undecalcified bone sections, accompanied by tetracycline double labeling and bone histomorphometry, the influence of different concentrations of fluoride on induced ectopic bone formation and mineralization during the 21th-30th day of the experiment was observed. Results showed that on the 30th day, the induced bone formation in the group of 50ppm NaF was more active than that of the control; and from the 21th day to the 26th day as well as from the 26th day to the 30th day, no inhibition of mineralization was obtained in the same group. The induced bone formation and mineralization in the group of 200ppm NaF was severely inhibited from the 21th day to the 26th day; on the 30th day, the quantity of induced bone was markedly reduced, and many woven bones were also present there.