Disclosed is a method for electing a root node in a mesh network, comprising the steps of: S1) when it is determined that there is no root node in the mesh network, all devices separately broadcast and transmit real-time signal strengths between the devices and a router; S2) all devices separately perform a first scanning, and each device elects, according to received real-time signal strengths between the other devices and the router and the real-time signal strength between the device and the router, a device having a maximum real-time signal strength as a root node candidate and broadcasts and transmits the same; and S3) all devices separately perform another scanning, and each device elects, according to the received root node candidates respectively elected by the other devices, a root node candidate having a maximum signal strength as a new root node candidate and broadcasts and transmits the same again until a unique root node is elected. According to the present invention, signal strengths and other information of devices may be transferred to one another in an entire mesh network, such that all devices may participate in comparison and voting to elect an optimal root node.