Abstract: Considering the high efficiency and stabilization, some operation data of a wastewater treatment plant using BAF process were analyzed through In order to evaluate the efficiency and stabilization of the biological aerated filter (BAF) process, the operation data of a wastewater treatment plant using BAF process, including COD, SS, ammonia nitrogen and total nitrogen, were analyzed through the average value method and the cumulative frequency method respectively. The results showed that, when the data were less fluctuated, both the average value method and the cumulative frequency method were suitable for analyzing the operation results of BAF process, and the average value method was more convenient and feasible. On the contrary, the cumulative frequency method was much better in reflecting the capacity and efficiency of BAF process when the data were more fluctuated. Based on the data analysis and practical experience, some operating suggestions of BAF were given on enhancing pretreatment, optimizing back-flushing and improving treatment effects, etc.