Abstract: Objective To establish amore economical,rapid,practical,and accurate method for detection of trace fluoride in biological,food and environmental samples.Methods The trace fluorideion in biologic,food and environmental samples or the digestive liquid wasm easured with microplate reader fluoride reagent spectrophotometry.The optmium expermiental conditions on reagent concentration,ratio and amount were decided with a 3 level of 4 factor orthogonal expermient design.The precision,accuracy sensibility,reproducibility,expermient linearity,and recovery rate were also determ ined by adding standard material into the samples.Results The new method could accurately measure the fluoride at the concentration of less than 0.06 g/mL.The correlation coefficient was 0.998 6 0.999 1.The lmiitation of the detection was 0.000 9 g.The testing accuracy was 0.001 g.The recovery rate was between 97.6% 100.12% and the coefficient variation was 2.65%.Conclusion The rapid,practical,economic,and simple method with a micro plate reader can be used to test trace fluoride in biological,food and environmental samples.The method is more accurate,precise,sensitive,and less tmie-consuming.