Designing a secure routing protocol to ensure the privacy of information and network security is a huge challenge of Internet of Things. In this paper, a new Core-Selecting mechanism is proposed, and the mechanism is applied to the design of routing protocol for the Internet of Things. Based on this, we designed and implemented a new secure routing protocol named PALXC for Internet of Things, which can help to resist internal collusion attack and select trusted route. Theoretical analysis and simulation experiment results show the effectiveness of the designed protocol.