Abstract: Based on the current nutrient level (ρ(TN) 5 mg/L and ρ(TP) 0.2 mg/L) in Meiliang Bay of Lake Taihu, the effects of nutrients concentration on the growth of Vallisneria atans were studied in controllable outdoor experiment. Results show that: ① Vallisneria atans can grow in those water bodies with nutrient level exceeding ρ(TN) 10 mg/L and ρ(TP) 0.4 mg/L, if the light compensation point can be satisfied and without existence of other macrophytes. ② The growth rate of Vallisneria atans showed a decreasing response to an increase in nutrient concentration, and the Vallisneria atans biomass began to decrease only when the nutrient levels exceeded ρ(TN) 10 mg/L and ρ(TP) 0.4 mg/L; there were few changes inVallisneria atans leaves, otherwise, rhizome biomass decreased following the increasing of nutrients, and all morphological date, except leaf length, decreased significantly when nutrients concentration exceeded ρ(TN) 10 mg/L and ρ(TP) 0.4 mg/L. ③ Based on the nutrient level in Meiliang Bay of Lake Taihu, doubling the phosphor content, compared to nitrogen, will much more suppress the macrophytes, and the negative effects will significantly increase when doubling both of them.