An investigation was made theoretically and experimentally on the porous biomass carrier sequencing batch reactor (PBCSBR) for enhanced nutrient removal. Biomass hold-up increased with incoming organic substrate concentration and held in attached and entrapped conditions. The behavioural patterns of organic carbon, nitrogen and phosphorus in PBCSBR were similar to the control SBR reactor. Nitrogen transformation and/or removal was simultaneous and stoichiometric and could be quantified by the stoichiometric relationship of nitrification/denitrification based on the consumed alkalinity. Phosphorus removal increased with biomass concentration and phosphorus release. Higher biomass and favorable operation mode in PBCSBR were conducive to enhanced nutrient removal.