This application provides a DRX configuration method, a terminal device, a network device, and a communications system. The DRX configuration method includes: receiving, by a terminal device, N discontinuous reception DRX configurations sent by a network device, where the N DRX configurations respectively correspond to N groups of carriers; and when a DRX status of the terminal device is an active state, if M groups of carriers in the N groups of carriers are activated carriers, monitoring, by the terminal device, a physical downlink control channel on a specified carrier based on M DRX configurations corresponding to the M groups of carriers. In the DRX configuration manner, the terminal device simultaneously uses a plurality of DRX configurations in an overlay manner, thereby meeting quality of service requirements of different services sent by the terminal device. In addition, the terminal device simultaneously uses the plurality of DRX configurations in an overlay manner, so as to reduce unnecessary physical downlink control channel monitoring in a process of monitoring the physical downlink control channel, thereby reducing energy consumption of the terminal device.