To avoid pollution of generator exhaust port after the ship docked, the use of shore power supply is developing direction of port. And the shore power grounding method and related standards needed to be carried out. According to developing status of foreign medium voltage ship and characteristics of navy shipboard power supply, this paper presents a shore power supply network structure and its grounding method. The simulation results show the power supply network structure can effectively suppress the single-phase intermittent ground fault on the system to produce the harm.