The invention provides a passive electronic tag antenna. The passive electronic tag antenna uses a printed circuit board double-sided board structure. The passive electronic tag antenna comprises an antenna main structure, a dielectric substrate, a through hole, underlying floor metal, a radio frequency signal port and a grounding port. The antenna main structure comprises an antenna conjugate matching structure. The antenna main structure is distributed on the top layer of the dielectric substrate. The underlying floor metal is arranged outside the area range on the bottom layer of the dielectric substrate and corresponding to the antenna main structure. The antenna conjugate matching structure is connected with the radio frequency signal port and the grounding port. The grounding port isconnected with the underlying floor metal through the through hole. According to the scheme, the integrated design technology is adopted, the tag antenna and the circuit structure are compactly combined together and the underlying floor of the circuit board is changed into one part of the antenna so that the size of the tag antenna can be reduced and the influence of the large-area floor structure of the circuit on the tag antenna can also be eliminated.