Since the tree based RFID tag anti-collision protocol achieves 100% read rate, and the slotted ALOHA based tag anti-collision protocol allows simple implementation and good performance in small amount of tags, we consider how to take the advantages of each algorithm. This paper presents query tree based reservation for efficient RFID tag anti-collision. According to the simulation results, the proposed protocol requires less time consumption for tag identification than the present tag anti-collision protocols implemented in EPC Class 0, Class 1, and Class 1 Gen. 2.