Abstract: The chemical agents of potassium permanganate, chlorine dioxide, copper sulfate and caustic lime were used to study their effects on the growth activity of Leptomitus lacteus symbiont. The variation of microbial biomass of Leptomitus lacteus symbiont before and after dosing the chemical agents was used to reflect the control effect. The water quality variation in water solution of Leptomitus lacteus symbiont before and after dosing the chemicals and the cost of them were analyzed. The results show that the four chemical agents all have some control effects on Leptomitus lacteus symbiont, and when their dosage were 1.5,1.5,2.0 and 40 mg/L, the maximum decrease rate of Leptomitus lacteus symbiont were obtained, being 68.0%,63.1%,67.0% and 76.8%,respectively. According to comprehensive comparison of the control effect on Leptomitus lacteus symbiont, the cost and the water quality variation before and after dosing the chemical agents, the sequence of the four chemicals for emergency from good to bad is chlorine dioxide>potassium permanganate>copper sulfate>caustic lime; while the sequence of treating after collection is caustic lime> potasslum permanganate>copper sulfate>chlorine dioxide.