Abstract-The main purpose of Radio-frequency identification (RFID) implementation is to keep track of the tagged items. The basic components of an RFID system include tags and readers. Tags communicate with the reader through a shared wireless channel. Tag collision problem occurs when more than one tag attempts to communicate with the reader simultaneously. Therefore, the second-generation UHF Electronic Product Code (EPC Gen 2) standard uses Q algorithm to deal with the collision problem. In this paper, we introduce three new anti-collision algorithms to handle multiple priority classes of tags, namely, DC, DQ and DCQ algorithms. The goal is to achieve high system performance and enable each priority class to meet its delay requirement. The simulation results reveal that DCQ algorithm is more effective than the DC and DQ algorithms as it is designed to flexibly control and adjust system parameters to obtain the desired delay differentiation level. Finally, it can conclude that the proposed DCQ algorithm can control the delay differentiation level and yet maintain high system performance.