The detection and isolation of hybrid multi-terminal DC line fault is an urgent problem. In this paper, aiming at the topology structure of hybrid multi-terminal DC system based on Line Commutated Converter (LCC) and Hybrid Half Bridge Modular Multilevel Converter (FHMMC), a multi-terminal DC line protection scheme is proposed. First, by configuring fast line protection system, the line fault is detected before the Modular Multilevel Converter (MMC) is over-currently blocked. Secondly, a configuration scheme is proposed in which the two ends of the converter station are configured with a line protection system to protect the full length of the DC line, and the intermediate converter station is configured with a line protection system to protect the two lines. Based on this, a line fault area identification criterion is constructed using the difference in current changes on both sides of the bus bar area after a line fault to solve the problem of multi-terminal line fault area identification. Finally, in cooperation with the control system, the DC voltage of the MMC station is controlled to zero or negative pressure, and the LCC station is quickly phase-shifted to realize self-clearing and isolation of line faults. The feasibility of the proposed strategy is verified by simulation. This work is supported by National Key Research and Development Program of China (No. 2016YFB0900603) and Science and Technology Project of State Grid Corporation of China (No. 52094017000W).