Disclosed are a method and system for establishing a route in a connectionless mesh network. The method comprises the following steps of: a sink device periodically broadcasting information to one or more surrounding devices of the sink device, wherein the information comprises information indicating the sink device as a sink, a MAC address of the sink device, and a signal strength between the sink device and an external router; a non-sink device periodically monitoring information broadcast by one or more surrounding devices of the non-sink device, and determining whether the information broadcast by the sink device is present; if so, the non-sink device selecting a sink device having a highest signal strength therewith as a next hop device, and the non-sink device periodically broadcasting information to the one or more surrounding devices of the non-sink device, wherein the information comprises a number of hops from the non-sink device to the sink device, a MAC address of the sink device, and the signal strength between the non-sink device and the sink device; if not, the non-sink device selecting a device having a highest signal strength therewith as the next hop device thereof, and the non-sink device periodically broadcasting information to the one or more surrounding devices of the non-sink device, wherein the information comprises the number of hops from the non-sink device to the sink device, a MAC address of the next hop device, and the signal strength between the non-sink device and the next hop device. The present invention may enable each device to find and maintain a route having the highest signal strength to a network sink.