Abstract: As a novel sustainable development technology, denitrifying phosphorus removal process (DPR) has attracted wide attention. In previous work, a novel denitrifying phosphorus removal process based on multistage anoxic-oxic process (DPR-MAO) was developed. In order to reveal the effect of the internal return system on nitrogen and phosphorus removal performance, the nitrogen and phosphorus removal efficiency of the DPR-MAO process under different internal return ratios was investigated. Meanwhile, the nitrogen and phosphorus removal process and the characteristics of the microbial community in each reaction tank were analyzed. As the internal return ratios increased from 100% to 200%, the total nitrogen (TN) and total phosphorus (TP) removal efficiency increased from 76.05% and 86.39% to 87.46% and 93.42%, respectively. The analysis of nitrogen and phosphorus mass balance revealed that the denitrifying phosphorus removal performance could be enhanced by increasing the internal return ratio. High-throughput sequencing results indicated that Thiothrix, Dokdonella, Candidatus accumulibacter, Thaurea, Comamonas, Dechloromonas and Pseudomonas were the dominant genus for denitrifying phosphorus removal. When the two internal return ratios were increased from 100% to 200%, the sum of relative abundance of genera with denitrifying phosphorus removal functions increased by 4 times, and the relative abundance of Thiothrix increased from 0.36% and 0.52% to 53.58% and 56.64%. The study demonstrated that the denitrifying phosphorus removal performance of DPR-MAO process and the dominant position of bacteria for denitrifying phosphorus removal could be enhanced by increasing internal return ratios.