The invention relates to a control method for a shore power source system. The control method comprises the steps as follows: (1) a two-way AC/DC converter lastingly detects voltage of an alternating current power grid and judges whether the shore power source system is in a normal operation state or not; if the shore power source system is in the normal operation state, the two-way AC/DC converter controls the stability of direct current bus voltage; and or else, the method goes to step (2); (2) the two-way AC/DC converter stops a stability control on the direct current bus voltage, and transmits an off-grid operation instruction to a two-way DC/DC converter, so that the two-way DC/DC converter controls the stability of the direct current bus voltage, also simultaneously detects the voltage of the alternating current power grid, and goes to the step (3) if the voltage returns to normal; or else, the step (2) lastingly runs; and (3) the two-way AC/DC converter restores the stability control on the direct current bus voltage again; and the two-way DC/DC converter retreats from the stability control on the direct current bus voltage. According to the control method for the shore power source system, the problem of voltage frequency and phase synchronization when an existing alternating current micro-grid shore power source system is converted into a grid connected state from an off-grid state can be effectively solved; the complexity of the system control is simplified; and the reliability is improved.