This application relates to the field of wireless communications technologies, and in particular, to a random access technology in an unlicensed frequency band. In a random access configuration method, a network device performs channel listening and obtains a channel occupancy time through contention. If a time-frequency resource used by a terminal device to transmit a random access preamble is configured in the channel occupancy time obtained by the network device through contention, the network device sends downlink control information to the terminal device, and the downlink control information is used to indicate configuration information for transmitting the random access preamble on the time-frequency resource. According to the solution provided in this application, the time-frequency resource for transmitting the random access preamble within the channel occupancy time may be dynamically configured, so as to flexibly use the channel occupancy time and improve communication efficiency in the unlicensed frequency band.