The present invention provides a connection device and method between a base band unit and a remote radio unit wherein the device includes: a first transmission multiplexer for implementing the optical transmission transceiving multiplex function of the base band unit a second transmission multiplexer for implementing the optical transmission transceiving multiplex function of the remote radio unit wherein the first transmission multiplexer connects to the second transmission multiplexer which enables the base band unit and the remote radio unit to perform data transmission through the first transmission multiplexer and the second transmission multiplexer. With the present invention the single line data transmission between the base band unit and the remote radio unit is achieved and the utilization ratio of the transmission line is improved. Fig.4
