A method and an apparatus for switching a cell state are provided, and relate to the field of communication technologies. The method includes: A terminal device receives a first instruction from a network device, and switches a serving cell state based on the first instruction. The first instruction indicates to switch the serving cell state of the terminal device to or from a first state. When the serving cell state is the first state, a downlink carrier of a serving cell supports downlink communication, and an uplink carrier of the serving cell does not support uplink communication.