The invention discloses a relay selection and frequency allocation method and device for a power wireless private network, and the method comprises the steps: transmitting a relay request to other terminal equipment in a coverage range of a base station when a business transmission demand cannot be met; receiving relay feedback information sent by other terminal equipment; selecting relay equipment according to the received service request and the relay feedback information, and sending a relay access request to the relay equipment; receiving a frequency resource fed back by the relay device according to the relay access request; and establishing a relay connection with the relay device according to the frequency resources. The invention provides a relay selection method of a power wireless private network. Compared with the prior art, the relay connection method has the advantages that the most appropriate terminal equipment is selected from numerous terminal equipment for connectionaccording to the received service request instead of taking the coverage range of the base station as a unique standard for selecting the relay equipment, and the transmission quality during subsequent service transmission is ensured through the relay connection established by the method.