The effects of different water depths and sediments on the growth of Potamogeton malaianus Miq. were studied from Sept. 2006 to Sept. 2007 at Taihu Laboratory for Lake Ecosystem Research. Experiments were carried out with Potamogeton malaianus in plastic pots from steel tubes placed on a concrete pond. Two types of sediments, mud and loess; and five water depths of 30, 60, 90, 120 cm and 150 cm were used in this experiment. The objective of the experiment was to determine the best growth habitat of Potamogeton malaianus and provide scientific basis for ecological restoration of submersed vegetation in Lake Taihu. The results show that water depth has a greater effect on the growth of Potamogeton malaianus than sediment type.With increased water depth, the length, dry biomass, and tiller numbers significantly changed; however, these indices experienced no significant changes between the two sediment types (mud and loess).Potamogeton malaianus had a stronger adaptability within water temperatures ranging from 22 to 30C and grows best in water depths ranging from 60-120 cm.In this range, plant length, relative growth rate (RGR) and dry biomass increased with water depth.The tiller numbers produced by Potamogeton malaianus plants also increased with time at these depths.In shallower or deeper water, the plant growth and reproduction may be limited due to many factors, such as light capacity or dehydration.Vegetative growth ability of Potamogeton malaianus decreased while reproductive ability increased through the whole winter.