The invention discloses a security protocol authentication method based on a mobile RFID system, and relates to the technical field of communications, for realizing security authentication by use of a method of a dynamic ID and a Hash function mechanism. In the authentication process of a protocol, a background server needs to carry out dual verification of an label identification ID and a mobile reader-writer identification RID and updates a label identification after verification succeeds, and an RFID label and a mobile reader-writer are each provided with a pseudorandom number generator and have capabilities of executing Hash operation and XOR logic operation. In each authentication process, a label, the mobile reader-writer and the background server perform transmission and exchange of encryption information, and through such processes of inquiry, response, search, calculation, verification, updating and the like, the effect of security authentication is realized. According to the invention, a new system can fend off various attacks by use of the dynamic ID and the Hash function mechanism.