This application provides a method and device for determining antenna port quasi co-location QCL. The method includes: generating, by a network device, downlink control information DCI, where the DCI includes QCL indication information, the QCL indication information is used to indicate one of a plurality of pieces of combination information, and first combination information in the plurality of pieces of combination information is used to indicate a QCL relationship between a DMRS antenna port and a CSI-RS antenna port; and sending, by the network device, the DCI to a terminal device. Therefore, in embodiments of this application, the terminal device can determine the QCL relationship between the DMRS antenna port and the CSI-RS antenna port based on the DCI, thereby resolving a problem in the prior art and improving network performance.