Abstract: With a large number of distributed generators connected to the power grid, the distribution network shows an obvious trend of power electronization. As a power conversion interface, the interactive stability of the inverter with the power grid can not be ignored. Reasonable impedance modeling of the three-phase grid-connected inverter is the premise of analyzing the stability and resonance characteristics of grid-connected systems. Harmonic linearization method has been widely concerned as an impedance modeling method with clear physical meaning. Taking the three-phase LCL inverter as the research object, the harmonic linearization model of typical phase-locked loop is established, and the impedance matrix characterizing the frequency coupling effect is obtained. On this basis, a simplified modeling method of harmonic linearization is proposed to model the impedance of three-phase LCL inverter with the typical capacitive current feedback control strategy. Furthermore, considering the interaction between the grid impedance and the inverter impedance matrix, the multi-input multi-output system model is transformed, and a single-input single-output positive and negative sequence impedance model suitable for the stability criterion is obtained. Finally,based on the PSCAD/EMTDC simulation platform, the accuracy of the proposed simplified harmonic linearization modeling method and the corresponding impedance model and the effectiveness for stability analysis are verified.