In AC/DC hybrid systems consisting modular multilevel converter based HVDC (MMC-HVDC), it needs the distance protection stage Ⅱ or stage Ⅲ of higher AC line action to remove fault when the protection of lower AC line which is directly connected with the MMC-HVDC cannot correctly removes fault zone. The changes of MMC-HVDC operation mode will result that the scope of higher line distance protection stage Ⅱ is narrowed. It has a great probability to refuse tripping. At this point it can only rely on distance protection stage Ⅲ to operate which may lead to fault clearing time extended. This paper carries out research on this issue, deeply analyzes the effects of MMC-HVDC operation mode on AC line distance protection. A complex characteristics distance protection based on the measurement information of MMC-HVDC common connection point is developed. This adaptive distance protection can reduce the adverse impact on the AC line distance protection and ensure the correct operation of the protection device to work. In PSCAD/EMTDC, AC/DC hybrid systems consisting MMC-HVDC is established to verify the proposed method and analysis. This work is supported by Science and Technology Development Plan of State Grid Corporation of China (No. NEDU20150002).