This application provides a secondary cell control method and an apparatus. The method includes: A terminal device receives control information in a time unit n, where the control information may include an activation command for a first secondary cell or a deactivation command for a first secondary cell. When the control information includes the activation command for the first secondary cell, first information of the first secondary cell is sent in a time unit n+k, where k is determined based on a first frame structure parameter configured for the terminal device, and both n and k are positive integers. The first information may be a CSI report.