Ecogeochemical features of epidemic fluorosis areas in Guangde Village of Anxi County were studied, and the results show that the F content of rock, soil, drinking water, paddy field and vegetables is relatively high, but Cu, Mo, Ca are gravely deficient. The content of F- is excessive, reaching as high as 4.18 mg/L, whereas the pH value of drinking water is below the standard of drinking water (6.5), and hence it is acidic, and not suitable for drinking. It is held that such an ecogeochemical environment is the main cause for endemic fluorosis.