An antenna feed coupling structure of a duplexer is disclosed to include a base defining a detoured resonance cavity and a T-shaped feed-in cavity perpendicularly intersecting the resonance cavity and a signal input port in connection with the head of the feed-in cavity, a cover closing the base, and adjustment rods mounted in the base and suspending in the resonance cavity and the feed-in cavity. The adjustment rods include two feed-in adjustment rods and two coupling structure adjustment rods suspending in the intersected area between the resonance cavity and the feed-in cavity and respectively kept in horizontal and in vertical relative to the resonance cavity and rotatable inwards and outwards to adjust the feed-in amount and coupling structure amount of the antenna feed coupling structure respectively.