Objective To understand thoroughly the effect of water improvement by investigating fluoride contents of drinking water in Meizhou fluorosis prevalent regions, the prevalence of fluorosis and the problems in water supply improvement projects. Methods In 2004, fluoride contents in drinking water were determined, 5 082 native pupils were examined for dental fluorosis according to Dean's method and the running status of water supply improvement projects was investigated also. Results After water supply improvement, the prevalence rate of the dental fluorosis in the fluorosis region(28.43 %) decreased significantly compared with that(56.99%) before the water supply improvement, the rate of fluoride content in drinking water that was up to standard reached 83.33%, the good running rate of water supply improvement projects was 68.42%. Conclusion The effect of water supply improvement is remarkable and satisfactory. In some regions little attention was paid to the management and daily maintenance of water supply but water source, which may cause water supply improvement projects damaged, in addition, water insufficiency and the alternate consumption of high fluoride water and normal water may be the main factors for fluorosis prevalence in some areas where although the water supply improvement has been finished.