A printed radio frequency sensor structure contains: a substrate, a RF antenna arranged on a top surface of the substrate, and a protection layer covering on the RF antenna arranged, wherein plural sensing materials are directly introduced into a RF antenna mixture of the RF antenna. A method of preparing a RFID sensor tag comprising steps of: A). Printing conductive sensing ink/glue on substrate; B. Drying, curing and compressing the conductive sensing ink/glue to form a conductive antenna mixture with plural sensing materials; C). Bonding a chip on a RFID sensing antenna to form a RFID sensor tag; and D). Coating a protection layer on a top of the RFID sensor tag. Here note protection coating can fully, partially or no cover the conductive sensing antenna.