Embodiments of the present application provide an information transmission method, a coordinator, and a terminal node in an optical wireless communications network. The method includes: receiving a request to send (RTS) frame sent by a sending node by using a first bandwidth, wherein the RTS frame comprises first indication information; determining a second bandwidth based on the first indication information, wherein the second bandwidth is a sending bandwidth used when the sending node sends to-be-sent information and a receiving bandwidth used when the receiving node receives the to-be-sent information; and sending a clear to send (CTS) frame to the sending node by using a third bandwidth.