Method and device for transmitting channel state information

The invention discloses a method and device for transmitting channel state information. The method comprises the step of generating a null data packet NDP, wherein the null data packet comprises an HE-LTF (high efficient long training filed) enabling a target STA to carry out channel estimation and a packet expansion field, or the null data packet comprises the HE-LTF enabling the target STA to carry out the channel estimation and extra HE-LTFs. Through application of the method and the device, resource waste resulting from the fact that partial stations do not support immediate feedback can be avoided, and further the efficiency of transmitting the channel state information can be improved.