A channel access indication method and device. The method includes: receiving, by a first communications device, a channel synchronization request sent by a second communications device, where the channel synchronization request is used to request the first communications device to send a synchronization frame to the second communications device, and a wake-up receiver is configured for the second communications device; and according to the channel synchronization request and a time at which the second communications device is woken up and that is learned by the first communications device based on preset signaling, sending, by the first communications device when a channel is idle, the synchronization frame to the woken-up second communications device, where the synchronization frame is used to instruct the woken-up second communications device to access the channel after receiving the synchronization frame.