A method to the determination of Iodide, Thiocyanate, Perchlorate and Glyphosate in drinking water by flow injection on-line preconcentration and Ion chromatography Spectrometry with activated carbon fiber as adsorbent was developed. Using the activated carbon fiber as adsorbent flow injection on-line preconcentration, and by flow injection in the laboratory (FIA)-ion chromatography (IC) combined with technology of adsorption column enrichment of Iodide, Thiocyanate, Perchlorate and Glyphosate were determined. The linear range of the method for trace Iodide, Thiocyanate, Perchlorate and Glyphosate was 0.01～5.00 mg/L, the correlation coefficients were 0.997 9, 0.999 0, 0.998 7 and 0.998 1, and the average recoveries were 94.9%～99.2%.