By means of the investigation in the five different townships with contrasting of the others, the main sources of fluorosis were found from pollution of the coal smoke, the content and total amount of fluoride intake from the maize and capsicum were calculated to be 74.35-94.72% by drying of the heat of burn coal and increased with the total amount of fluoride intake. The clear doses of the prevalence rates of dental fluorosis, the mean output of urinary fluoride and the total amount of fluoride intake--response relationship, showing a semilogarithmic positive correlation between 8 and 15 years of age. At the age the prevalence rates of bad incomplete teeth and milk-teeth showed a linear correlation with the total amount of fluoride intake and the mean output of urinary fluoride respectively. And seven regression equations were calculated. The question concerning the epidemic fluorosis districts caused by burn coal was discussed. We suggest that sick districts can be affirmed on the basis of the total amount of fluoride intake, the prevalence rates of dental fluorosis, bad incomplete teeth, milk-teeth and the mean output of urinary fluoride between 8 and 15 years of age.