A method and device for notifying and determining De Modulation Reference Signal (DMRS) ports or a mapping relationship is provided. The method includes: a sending end sends indication information to a receiving end in a Transmission Mode (TM), and the sending end indicates allocation information about DMRS ports or a mapping relationship according to the indication information, and the indication information includes at least one of the following: Radio Resource Control (RRC) signaling, physical layer New Data Indication (NDI) bit, and DMRS pilot scrambler configuration information nscid. A problem of influence on a performance of a Multi-User Multiple-Input Multiple-Output (MU-MIMO) system caused by lower channel estimation performance due to limited orthogonal DMRS ports for MU-MIMO transmission and high Multi-User Interference (MUI) after increment of a total number of MU-MIMO transmission layers is solved, thereby increasing orthogonal DMRS ports for MU-MIMO transmission on a basis of improving base station configuration flexibility during MU-MIMO transmission, effectively inhibiting MUI during channel estimation, and improving channel estimation performance.