Biological treatment of domestic sewage low C/N ratio was accomplished in a pilot-scale sequencing batch biofilm filter (SBBF). The novel hybrid bioreactor consisted of bio-band in the upper and anthracite filter media in the bottom, which combined a sequencing batch biofilm reactor (SBBR) with a biological filter. The average removal efficiency values of chemical oxygen demand (COD), ammonium nitrogen (NH4 (+)-N), total nitrogen (TN), and total phosphorus (TP) were 89.4, 83.3, 62.9, and 48.7%, respectively. A 454-pyrosequencing technology was employed to investigate the microbial communities of the influent (J1) and the biofilm (J2) on the bio-band on day 40. Pyrosequencing analysis of the 16S rRNA gene revealed the community of the biofilm consisted of Gammaproteobacteria (48.6%), Planctomycetacia (18.0%), Alphaproteobacteria (13.7%), Clostridia (9.6%), Desulfonatronum (18.5%), Actinobacteria (1.9%), and Bacilli (1.7%), accounting for 93.6% of total operational taxonomic units at genera level. Acinetobacter tjernbergiae and Acinetobacter lwoffii were the most abundant species, suggesting that denitrifying phosphorus removal was achieved in the SBBF.