Abstract: Active Network is a new model network，and it has applied in some fields.The Demand Loading Code Protocol is based on mobile code，demand loading，and cache techniques that allow new protocols and service to be dynamically deployed.Because of the Demand Loading Code Protocol exist replay attack，letdown the performance and efficiency of network，so this paper presents a new effective protocol based on hash function，active node needn’t decryptions the packet to detect the replay attacker，and enhance the capacity for replay attack.Its security and computational overhead are analyzed in detail.