Abstract: The boundary of sending and receiving ends of hybrid multi-terminal DC transmission system is asymmetric, and the boundary of the T-zone is not obvious. The existing DC transmission line protections are difficult to be directly applied and suffer from problems such as insufficient resistance to fault resistance and failure in considering the identification of T-zone faults. To this end, a single-ended protection scheme for hybrid multi-terminal DC transmission lines based on intrinsic mode feature vectors is proposed. First, the frequency characteristics of line boundaries and T-zones are analyzed. Combined with the variational mode decomposition algorithm, the fault signal is decomposed adaptively. On this basis, the intrinsic modes that are conducive to amplifying the feature differences between internal and external faults are screened. Second, the protection feature matrix is constructed by using the filtered modal amplitude to make full use of the fault information, and the dimensionality reduction method from matrix to vector is proposed to reduce the computational effort. Aiming at the disunity of the eigenvector dimension caused by the screening process, a vector element merging criterion based on the modal center frequency is established to reconstruct the vector with uniform dimension. Finally, according to the obvious difference in the amplitude of the eigenvector corresponding to internal and external faults, a single-end protection criterion based on vector distance is proposed. Simulation results show that the proposed protection can accurately identify the terminal faults under different conditions, and has high reliability, strong resistance to fault resistance (500 Ω) and anti-noise ability (20 dB).