In the RFID system,it is possible to produce a data collision phenomenon when multiple electronic tags send information to the reader, to solve this problem,based on the analysis and research of the dynamic frame slot ALOHA algorithm and backoff binary search algorithm,we proposed an improved algorithm combining the two.The algorithm absorbs the advantages of fast of ALOHA algorithm and high efficiency of binary algorithm,simultaneously it can estimate the number of remaining tags within the system and adjust frame length dynamically,then makes the system work in the optimal state.Theoretical analysis and simulation results show that the improved algorithm is better than the traditional anticollision algorithm.It can effectively improve the system throughput and reduce the number of slots required for the query tag at the same time.