The invention discloses a control method and system for a shore variable-frequency power supply to suppress the no-load closing excitation inrush current of a transformer. The method includes the steps of extracting the main frequency component of excitation inrush current as the control and regulation feedback of a variable-frequency power supply and implementing additional virtual damping control design and fundamental wave voltage instruction optimal generation design. In the actual connection process, a circuit breaker connected between the transformer and the variable-frequency power supply is closed first, and the inrush current suppression during the excitation process of the transformer from zero voltage to rated voltage is realized through the control optimization design of a variable-frequency power supply controller. The method of the invention makes full use of the controllability of the three-phase variable-frequency power supply in the marine shore power system. The goalof improving the success rate of connection between the variable-frequency power supply and the transformer is achieved. Moreover, there is no need for additional hardware cost, and high economy and strong engineering practicability are achieved.