Abstract: A kind of UHF ultra compact passive RFID tag antenna reducing size by high dielectric constant substrate and extending electric length by slot was presented. Affection due to metal objects was taken into account. Then antenna model was built by CST MWS software impedance matching between tag antenna and RF chip was analyzed with several dimension varied. Then screen printing process was taken to produce a sample tag and compared with the performance to theoretical calculated result. Experiment shows good impedance matching has met and the readable range can reach more than 2m with tag size of 12mm×7mm×3mm. This kind of tag is metal mountable and could be widely applied in compact metal tools management on the Internet of Material Distribution.