Abstract: A cross-network wake-up method and a related device. In the method, an Internet of things platform sends a wake-up instruction to an agent device that maintains a heartbeat connection to the Internet of things platform, and then sends, through the agent device, a wake-up message to a to-be-woken-up Internet of things device that is deployed on a same private network as the agent device. This resolves a technical problem that after a public-private network address mapping becomes invalid, a message from the Internet of things platform cannot reach the Internet of things device through a NAT device, and the Internet of things device cannot receive the message.