This paper designs a multifunctional grid-connected inverter (MFGCI) .It can both utilize the energy in green energy resource (GER) and energy storing device (ESD) and alleviate the harmonic pollution caused by propulsion system in ship power grid properly. Simultaneously, the volume of propulsion transformer is expected to be reduced and the PFD will be less-used or even out of work. The result of simulation verifies the validity of alleviating the harmonic wave in the power grid by using MFGCI.