The significance of obtaining the inverter impedance is self-evident for the analysis of the oscillation of the inverter integrated system. However, it is costly to conduct impedance measurements by an additional perturbation injection device. For a system with multi-inverter, the inverter impedance can be measured by the perturbation injected by other inverters within the system. In this paper, a novel method is proposed for the impedance measurement of multi-inverter grid-connected system, which does not require an additional device to generate perturbation and the perturbation required for measurement is generated by the inverter with perturbation control module. Considering the influence of grid frequency deviation on impedance measurement of inverters, the detected frequency of the phase-locked loop is applied for perturbation control module to generate negative-sequence perturbation. Impedance measurement of a two-inverter-connected system was conducted for the verification of the accuracy of the proposed method in the simulation case, which proves that the perturbation injection method with frequency feedback can obtain more accurate impedance results of the measured inverter #1 in the system with frequency deviation.