Abstract: Aiming at the security problem of the existing routing protocols in wireless sensor networks,an improved Directed-Diffusion protocol is proposed.In this protocol,some technologies,such as symmetric encryption,message integrity check code,and short signature,are used to implement the security properties of each protocol message packet,such as privacy,fresh,and integrity.Therefore,in this case,the proposed routing protocol can defend main route attacks, such as spoofed routing information,Sybil attack,and acknowledgement spoofing,in despite of the active adversary or the passive adversary.To raise the security level of the Directed-Diffusion routing protocol in wireless sensor networks is quite useful for saving the energy of the network nodes and maintaining the continuous usability.Through comparisons and analyses,the proposed Directed-Diffusion protocol is a comparatively efficient and secure one,which can achieve the secure route establishment at the cost of only a little performance in communication and computation.