Relay transmission method, device and system

The invention discloses a relay transmission method. The method includes that macro network nodes broadcast covered all user device information to covered all micro network nodes, and the micro network nodes determine at least one user device to provide relay service; the macro network nodes select one micro network node to provide the relay service for each user device from at least one micro network node and transmit a time slot resource allocation policy corresponding to each user device to the corresponded micro network nodes; the micro network nodes transmit downlink data transmitted by the micro network nodes for the corresponding user devices according to the time slot resource allocation policy and occupy the lengths of sub-time slot resources, except those required to provide relay services, to transmit or receive data, to be transmitted to the corresponding user devices not by the macro network nodes.. By the aid of the scheme of the embodiment, the data transmission velocity is improved, and the utilizing rate of spectrum resources is increased.