Abstract: The effect of water depth gradient on the growth and nutrient removal rate of the submerged macrophytes Potamogeton malaianus, a dominant species in Taihu Lake, was examined in an outdoor pond experiment. At the beginning of the growth period, lower water depth increased the grewth rate of P. malaianus. The growth rate reached 2.04 cm/d at the water depth about 60 cm,while 0.88 cm/d at the water depth about 180 era. During 82 days growth period, the stem height of P. malaianus was 180 cm and the growth rate was 2.04 Cm/d, while the stem height was 86 cm and the growth rate reached only 1.07 cm/d at 60 cm water depth. The stem height and the water depth was positive correlation along the water depth gradient. The biomass of P. malaianus ranged from 810 g/m3 to 2 941 g/m3. The biomass and stem height increased with the water depth. The aboveground concentration of nitrogen and phosphorus of P. malaianus was 86.43 mg/g and 5.12 mg/g, respectively at the 100 cm water depth. The TN and TP removal rate also reached the highest value of 87.6 mg/g and 40. 1 mg/g, respectively at the 100 cm water depth. Compared with the TN removal rate, TP removal rate was relatively low in the different water depth gradient. TN removal rate of P. malaianus was 2.87 times of its TP removal rate. The biomass and density of P. malaianus showed an active response to the water depth gradient. The experiments showed the optimal water depth on the growth of P. malaianus and its TN and TP removal rate was 100 cm.