Abstract: The present disclosure belongs to the technical field of water body treatment, and particularly relates to a method for enhancing biological denitrification based on the addition of exogenous ?-cyclodextrin. Preferably, Paracoccus denitrificans and ?-cyclodextrin are added for biological denitrification enhancement. In the present disclosure, the ?-cyclodextrin is exogenously added to a denitrifying medium to construct a denitrification system, so that the denitrification rate of microorganisms may be increased and the production of harmful denitrification intermediate products is reduced.