In the communication of RFID system, it is easy to cause collision during data exchange between the tag and the reader, thus tags may not be identified. On the basis of researching binary algorithm, bit positions of collision are locked through setting different statuses of the order during collision, and then samples of the locked positions are recorded to select the remaining collision positions during the paging process to the descending order. Compared with traditional binary collision algorithm, significant improvements have been made in analyzing the algorithm’s indexes like searching times, amount of communication and throughput, improving efficiency of the system.