This paper proposes a novel method to suppress tag collision in the ISO 18000-6 type B protocol which is one of the standard protocols of UHF RFID systems. The anti-collision performance in terms of the total identification time is improved by reducing the length of bits and the number of transmission commands required for multi-tag identification in the ISO 18000-6 type B protocol. Simulation results show that the proposed method improves the multi-tag identification time by about 15% over the conventional method, irrespective of the number of tags.