To solve the problem of too much identifying times and data transmission in some binary tree-based algorithms, an enhanced binary tree-based anti-collision algorithm for Radio Frequency Identification (RFID) system was proposed. The algorithm makes full use of the information of last query, and tags respond to reader in succession according to the first collided bit. Therefore, the probability of collision can be decreased. Reader stops receiving remaining bits immediately while detecting two collision bits in the received data, which can reduce the transmission of redundant data. The algorithm divides all tags into many subsets and adopts backtracking strategy. The simulation results show that the algorithm significantly improves the identification efficiency.