The influence of glucose, methanol, sodium acetate and starch on phosphorus removal performance and conversion of phosphorus transformation is studied. The results show that 42.05 mg per day of external phosphorus is removed in the systems using glucose as carbon source and it is significantly better than the other three carbon sources. When glucose is used as carbon source, NaOH-P and BD-P which are main ingredients of Inorg-P in system sludge transform 1.67 mg per gram dry sludge, and conversion capacity of NaOH85-P is relatively higher. The whole phosphorus transformation process goes toward reactive phosphorus which can be used by phosphorus reducing bacteria. When starch is used as carbon source, conversion capacity of Org-P in sludge is lowest for 2.86 mg per gram dry sludge, which is the restrictive process of entire phosphorus transformation. When starch is used as methanol, sodium acetate, conversion capacity of NaOH85-P in sludge is relatively low and BD-P is difficult to transform, which is the restrictive step of entire phosphorus transformation.