A transmit power determining method and apparatus are disclosed. The method includes: calculating, channel state information of a channel between the wireless access point device and a station device within a particular time range; comparing, by the wireless access point device, the channel state information with pre-obtained reference channel state information, and adjusting, according to a result of the comparison, a transmit power currently used by the wireless access point device; and sending, by the wireless access point device to the station device by using a transmit power after the adjustment, a message carrying data. During implementation of the present disclosure, a transmit power for sending data can be adjusted according to channel state information corresponding to a channel between a wireless access point device and a station device, thereby avoiding unnecessary power overheads and a waste of energy.