The paper studied the effect of NO-2-N on denitrifying phosphorus removal by DPAOs in batch tests in different conditions of electron and MLSS and compared the result with that of NO-3-N as electron acceptor. The results showed that NO-2-N can be taken as electron acceptor used by DAOs for denitrifying phosphorus removal, phosphorus uptake inhibition is induced by excessive NO-2-N. Moreover, NO-2-N as electron acceptor might be involved in denitrifying phosphorus removal and endogenous denitrification at the same time.The result shows that the increase of MLSS can improve anoxic phosphorus removal, while excessive mixed liquid suspended solids (MLSS) will reduce phosphorus uptake rate of unit sludge. So it is necessary to reasonably control MLSS concentration in denitrifying phosphorus removal.