Abstract: Submerged plant were paid wide attention to by both at home and abroad for its purification capacity on polluted water body. The purification ability of Hydrilla verticillata on simulated wastewater was studied under the temperature of 4 ℃ and the light intensity of 500-800 lx, and the nitrogen removal effects under different dosages of Hydrilla verticillata in simulated waterwater were investigated. The results showed that Hydrilla verticillata could maintain life activities in the low temperature conditions in the experimental period. Simultaneously, the pH of water was improved to over 8, and the concentration of dissolved oxygen maintained in 3-5 mg/L by the photosynthesis of Hydrilla verticillata. When the dosage of Hydrilla verticillata was 17.5 g/L, the highest removal rate of NH₄⁺-N and TN could be obtained, being 25.29% and 20.97%, respectively. Due to the addition of Hydrilla verticillata, the plant uptake capacity of nitrogen was intensified, and the nitrification, denitrification and ammonia volatilization were also strengthened due to the change of micro environment of the system, thus realizing intensive removal of nitrogen in the water.