A method for calculating a Channel Quality Indicator, CQI, comprising the steps of: determining, by a terminal device, K ports used to calculate a channel quality indicator CQI in N ports, wherein N is a number of ports in a channel state information-reference signal, CSI-RS, resource, and K is associated with a rank; calculating, by the terminal device, the CQI for the rank based on the K ports; and reporting, by the terminal device, the CQI and the rank to a network device, wherein the rank is equal to K, and K and N are positive integers; wherein when the terminal device does not receive information sent by the network device, the determining, by a terminal device, K ports used to calculate a CQI in N ports comprises: selecting, by the terminal device, preconfigured K ports from the N ports according to the rank; wherein before the determining, by a terminal device, K ports used to calculate a CQI in N ports, the method further comprises: when receiving, by the terminal device, first configuration information sent by the network device, wherein the first configuration information is used to indicate a sequence comprising the port information of the K ports; the determining, by a terminal device, K ports used to calculate a CQI in N ports comprises: determining, by the terminal device, the K ports in the N ports according to the first configuration information. determining, by a terminal device, K ports used to calculate a channel quality indicator CQI in N ports, wherein N is a number of ports in a channel state information-reference signal, CSI-RS, resource, and K is associated with a rank; calculating, by the terminal device, the CQI for the rank based on the K ports; and reporting, by the terminal device, the CQI and the rank to a network device, wherein the rank is equal to K, and K and N are positive integers; wherein when the terminal device does not receive information sent by the network device, the determining, by a terminal device, K ports used to calculate a CQI in N ports comprises: selecting, by the terminal device, preconfigured K ports from the N ports according to the rank; wherein before the determining, by a terminal device, K ports used to calculate a CQI in N ports, the method further comprises: when receiving, by the terminal device, first configuration information sent by the network device, wherein the first configuration information is used to indicate a sequence comprising the port information of the K ports; the determining, by a terminal device, K ports used to calculate a CQI in N ports comprises: determining, by the terminal device, the K ports in the N ports according to the first configuration information. selecting, by the terminal device, preconfigured K ports from the N ports according to the rank; wherein before the determining, by a terminal device, K ports used to calculate a CQI in N ports, the method further comprises: when receiving, by the terminal device, first configuration information sent by the network device, wherein the first configuration information is used to indicate a sequence comprising the port information of the K ports; the determining, by a terminal device, K ports used to calculate a CQI in N ports comprises: determining, by the terminal device, the K ports in the N ports according to the first configuration information. when receiving, by the terminal device, first configuration information sent by the network device, wherein the first configuration information is used to indicate a sequence comprising the port information of the K ports; the determining, by a terminal device, K ports used to calculate a CQI in N ports comprises: determining, by the terminal device, the K ports in the N ports according to the first configuration information.