Based on the oxidation effect of chlorine residual on potassium iodide and iodostarch reaction, a new method of determination chlorine residual named potassium iodide starch paper method is presented in this paper. 基于余氯对碘化钾的氧化作用和碘淀粉反应,本文提出了测定余氯的碘化钾-淀粉试纸法。