Abstract: The multi-feed multilevel A/O biological nitrogen removal process has distinct advantages in nitrogen removal.Currently,the researches all over the world on the multi-feed biological nitrogen removal process are limited only on the process emulation and synthetic-sized wastewater.By using real-wastewater simulate with the multi-feed process,the operational characteristics and the optimal controlled operation were more comp retentively investigated with 3 steps each with different ρ(C)/ρ(N) ratios.