Embodiments of the present disclosure provide a method and an apparatus for transmitting channel state information. The method includes: receiving, by a first terminal device, downlink control information DCI transmitted by a network device; determining, by the first terminal device, according to the DCI, whether it is necessary to report CSI; and when the first terminal device determines that it is necessary to report the CSI, transmitting, by the first terminal device, the CSI of the first terminal device to the network device. The first terminal device may be triggered to report the CSI according to the DCI transmitted by the network device, and thus the terminal device may report its own CSI.