An LAA-based wireless transmission access method is disclosed including: acquiring, by a BBU, a signal format corresponding to an LBT startup indication, and delivering a corresponding LBT startup indication message; distributing, by a bridge unit, the startup indication message to an RRU; performing, by the RRU, spectrum scanning according to the signal format to obtain idle/busy state information of an unlicensed spectrum in the signal format, and reporting the same to the BBU via the bridge unit; determining, by the BBU, a preemptable unlicensed spectrum in the signal format according to the idle/busy state information, and delivering an occupancy message; delivering, by the bridge unit, the occupancy message to the RRU; determining, by the RRU, a signal source of the signal format in the occupancy message; if the signal source is a different manufacturer, switching to an intermediate radio frequency processing channel of a different manufacturer for transmission.