Implementations of the present disclosure disclose a method for switching a status of a secondary carrier, a terminal device, and a network device. The method comprises: a terminal device receiving a media access control (MAC) control element (CE) sent by a network device; and the terminal device switching a first secondary carrier of the terminal device from a first state to a second state according to the MAC CE, wherein the first state and the second state are two different states of an activated state, a deactivated state, and a dormant state.