Abstract: This paper reviews the current research status of existing secure routing protocols in Wireless Sensor Networks (WSN) environments. Targeting the characteristics of WSNs, it analyzes the security deficiencies of existing protocols, the security threats they face, and their defense mechanisms. A new trusted route discovery algorithm, Trust_DD, is proposed and implemented in a Direct Diffusion routing protocol. Simulation experiments using the NS2 network simulation tool demonstrate the effectiveness of the algorithm. It not only minimizes resource consumption but also defends against selective forwarding attacks and significantly increases network throughput. Keywords: Wireless sensor network; Secure routing protocol; Trustworthiness; Selective forwarding attack; NS2 simulation 1. Introduction The security problems of newly emerging wireless sensor networks differ from those of traditional wireless networks, and existing network security protocols are not suitable for wireless sensor networks. WSN applications are mainly in military defense, disaster relief, and remote monitoring of dangerous areas, requiring high security. However, WSNs inherently have some security weaknesses, making research on wireless sensor network security essential. Dynamic topologies make it easy for hackers to interfere with the routing update information exchanged between nodes. Routing algorithms require cooperation among multiple nodes. Some untrusted nodes may refuse to cooperate, terminating route forwarding and causing network communication interruptions. Existing WSN routing protocols assume that all nodes within the network are trustworthy, neglecting the issue of attack vulnerability. Therefore, existing protocols are highly susceptible to both active and passive attacks. This paper investigates the trust level of routing between nodes, establishes a trust model suitable for wireless sensor networks, designs a trust-based secure and reliable discovery algorithm, and studies its feasibility through simulation experiments. [Full text of "Trusted Route Discovery Algorithm for Wireless Sensor Networks" available for download.]