With static laboratory experiments,Ceratophyllum demersum was selected as the research object to investigate its phosphorus (P) uptake abilities for different P levels of inorganic and organic phosphorus.Phosphorus uptake kinetics was also studied by ion depletion method.The results show that the average daily P accumulation in Ceratophyllum demersum increased significantly during the 30 days experimental period.P uptake ability by Ceratophyllum demersum in different inorganic P (KH2PO4) levels was obviously enhanced with the increasing phosphorus concentration.Moreover,Ceratophyllum demersum can uptake and utilize β-glycerophosphate as P source no matter whether the systems were sterilized or not,which indicates there is no microorganisms dependence in the uptake of β-glycerophosphate by Ceratophyllum demersum,but for phytic acid,almost no P uptake was detected.The uptake ability of organic P by Ceratophyllum demersum was much higher than that of inorganic P at the P level of 10 mg/L.The P uptake kinetics parameters were calculated according to the experimental data.The maximum absorption rate(Imax) of P by Ceratophyllum demersum is 54.94 μg P/g·h (Dry Weight) and the Michaelis constant(Km) is 1.754 mg/L,which shows that the maximum absorption rate of P by Ceratophyllum demersum is relatively low compared with other wetland plants and the affinity of P with Ceratophyllum demersum is rather weak.