This application relates to the field of wireless communication technologies, and in particular, to a time control, an apparatus, and a system. This application provides a timer control method, including: When downlink control information indicates data transmission of N hybrid automatic repeat request (HARQ) processes and a terminal device is configured with the N HARQ processes, where N is an integer greater than or equal to 2, a discontinuous reception inactivity timer is not started or the discontinuous reception inactivity timer is stopped. This application reduces time required by the terminal device to monitor a downlink channel or downlink data through control by the timer, thereby reducing power consumption of the terminal device.