To achieve energy-efficient denitrifying phosphorus removal via nitrite pathway from sewage, interaction of "Candidatus Accumulibacter" and nitrifying bacteria was investigated in a continuous-flow process. When nitrite in returned sludge of secondary settler was above 13 mg/L, nitrite inhibition on anaerobic P-release of polyphosphate organisms (PAOs) occurred. Clades IIC and IID were dominant, reaching 3.1%-11.9% of total bacteria. Clade IIC was sensitive to nitrite. Under low concentration of nitrite (< 8 mg/L), Glade IIC primarily contributed to anoxic P-uptake. Clade IID had a strong tolerance to nitrite exposure. At high nitrite level (above 16 mg/L), anoxic P-uptake was mainly performed by Glade IID due to its strong tolerance to nitrite exposure. Ammonia oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB) and Accumulibacter interacted through variations of nitrite accumulation. High AOB abundance coupled with inhibition of NOB favored denitrifying phosphorus removal by Glade IID. All Accumulibacter lineages were sorted into four clades of Type II. The most dominant ppk1 gene homologs were affiliated with Glade IID, accounting for 69% of ppk1 clone library, and thus played an important role in denitrifying phosphorus removal via nitrite pathway.