The invention discloses a shape-adjustable double ring-shaped ultrahigh frequency RFID (Radio Frequency Identification) tag antenna, which belongs to the technical field of radio frequency identification. In the tag antenna, two conductor rings are produced on one side of a basal plate and are taken as an antenna structure, wherein an inner ring is a closed conductor ring connected with a chip, an outer ring is one conductor ring provided with an inverse Z-shaped notch, the rings can be in the shape of a round or a rectangle or in other shapes, and the performance is little changed. The tag antenna can be applied to frequency ranges such as UHF (Ultra High Frequency) or ultrashort waves and the like; the size is only 32*32*0.8mm<3> (0.1*0.1*0.002Lambada<3>) if the structure of the shape-adjustable double ring-shaped ultrahigh frequency RFID tag antenna is adopted by taking the condition that center frequency is 915MHz and the chip adopts Monza4 as an example, so that very high efficiency, omni-directionality and wide applicability can be achieved, and the shape-adjustable double ring-shaped ultrahigh frequency RFID tag antenna can be applied to other chips and operating frequencies after being adjusted simply. The invention provides a method which solves the further miniaturization problem of the tag antenna, wherein the method is especially suitable for being applied to the field of needing miniaturization and omni-directionality of the tag antenna and having special requirements on the shape of a tag.