MSC 101 of International Maritime Organization (IMO) Maritime Safety Committee adopted the SOLAS Amendment including Maritime Autonomous Surface Ships (MASS) by Resolution MSC.456 (101), which is expected to come into force on January 1, 2024. The Amendment divides the MASS into four levels: Level 1, Level 2, Level 3 and Level 4. The arrangement of the main propulsion system for MASS merchant ships with diesel engine as the main propulsion system should also be adjusted according to the Amendment. Different configuration requirements of the main propulsion system are proposed for the four levels of MASS to provide reference for the relevant personnel.