The invention discloses methods for enhancing robustness of a multiple-inverter parallel grid-connected system to power grid impedance. The method 1 comprises the steps of: detecting capacitance current, grid-connected current and PCC point voltage of each inverter; calculating to obtain an error signal e1k; calculating to obtain an error signal e2k; acquiring a driving signal controlling an inverter switching tube on the basis of the error signal e2k; judging whether a grid-connected current peak value ig1 is greater than a set grid-connected threshold value iT; and if so, switching on a capacitance branch circuit, otherwise, switching it off. The method 2 comprises the steps of: detecting capacitance current iCk, grid-connected current igk and PCC point voltage; calculating to obtain an error signal e1k; calculating to obtain an error signal e2k; and acquiring a driving signal controlling the inverter switching tube on the basis of the error signal e2k. The methods provided by the invention can ensure stable performance of the multiple-inverter parallel grid-connected system when a power grid impedance wide range changes, and have the advantages of being simple and practical, high in reliability and low in cost.