This experiment examined the purification effect of two submerged plants (Hydrilla verticillata and Vallisneria natans) on rural pond, and the nitrogen and phosphorus removal function of the plants in water, which was experimentized in pilot sink.The results showed that the plants can significantly decrease the concentration of total nitrogen, ammonium nitrogen, nitrate nitrogen, phosphate with a removing rates reached 50.5%, 84.4%, 41.9%, 64.6%, respectively. The density of H. verticillata and V. natans setting to be 20 g/m², and 40 g/m² would be the best options. As water flew through the series unit, there was obviously difference in nitrogen and phosphorus removal efficiency.The removal rates on total nitrogen, nitrate nitrogen, phosphate in planting area were higher than the ones in open area, while to the removal rate on ammonium nitrogen, is higher in open area. Combining dissolved oxygen of the units and the total number of nitrification and denitrification bacteria, it showed that plant units may have significant denitrification, while open units have significant nitrification. Tandeming the open unit and planting unit together could have a better total nitrogen removal effect.