Abstract: Multiple power supply modes exist in marine electric power systems with both diesel generators and inverters. Since the short-circuit characteristics of inverters differ from those of diesel generators, the short-circuit characteristics of an electric power system are different for each power supply mode. Traditional power system protection technology based on the time-current principle is not suited to marine electric power systems with multiple power supply modes. To solve this problem, novel protection strategies that are suitable for marine electric power systems with multiple modes are developed using the local electric information of the breakers, and the inverters and load circuit breakers are configured and set on the basis of inverse-time over-current protection with low voltage acceleration. The simulation results indicate the selectivity and speed of short-circuit protection technology in the supply modes of diesel generators and inverters. In brief, this technology provides references for designing similar marine electric power systems.