A method of transmitting a CSI report, a terminal device and a network device are provided. The method includes: determining a target PUCCH resource; in a case that a payload of a CSI report set to be put into the target PUCCH resource is larger than a transmission capacity of the target PUCCH resource meeting a target code rate, placing a part of the CSI reports of the CSI report set into the target PUCCH resource, according to priorities of the CSI reports; in a case that the payload of the CSI report set is smaller than or equal to the transmission capacity of the target PUCCH resource meeting the target code rate, placing all the CSI reports of the CSI report set into the target PUCCH resource; and sending the placed CSI reports on the target PUCCH resource.