A method for switching a state of a secondary carrier, comprising: receiving, by a terminal device, a Media Access Control, MAC, Control Element, CE, sent by a network device; and switching, by the terminal device according to the MAC CE, a first secondary carrier of the terminal device from a first state to a second state, wherein one of the first state and the second state is a dormant state, and the other is an activated state, or a deactivated state; wherein when the MAC CE is a first MAC CE, the first MAC CE is used for indicating: switching the first secondary carrier from the activated state or the dormant state to the deactivated state, when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value, and switching the first secondary carrier from the deactivated state to the activated state, when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value; wherein when the MAC CE is a second MAC CE, the second MAC CE indicates: switching the first secondary carrier from the activated state or the deactivated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value; and switching the first secondary carrier from the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value. receiving, by a terminal device, a Media Access Control, MAC, Control Element, CE, sent by a network device; and switching, by the terminal device according to the MAC CE, a first secondary carrier of the terminal device from a first state to a second state, wherein one of the first state and the second state is a dormant state, and the other is an activated state, or a deactivated state; wherein when the MAC CE is a first MAC CE, the first MAC CE is used for indicating: switching the first secondary carrier from the activated state or the dormant state to the deactivated state, when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value, and switching the first secondary carrier from the deactivated state to the activated state, when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value; wherein when the MAC CE is a second MAC CE, the second MAC CE indicates: switching the first secondary carrier from the activated state or the deactivated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value; and switching the first secondary carrier from the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value. switching the first secondary carrier from the activated state or the dormant state to the deactivated state, when a value of a bit corresponding to an index of the first secondary carrier in the first MAC CE is a first value, and switching the first secondary carrier from the deactivated state to the activated state, when the value of the bit corresponding to the index of the first secondary carrier in the first MAC CE is a second value; wherein when the MAC CE is a second MAC CE, the second MAC CE indicates: switching the first secondary carrier from the activated state or the deactivated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value; and switching the first secondary carrier from the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value. switching the first secondary carrier from the activated state or the deactivated state to the dormant state when a value of a bit corresponding to an index of the first secondary carrier in the second MAC CE is a first value; and switching the first secondary carrier from the dormant state to the activated state when the value of the bit corresponding to the index of the first secondary carrier in the second MAC CE is a second value.