Abstract: The DC component injection issues exist in the non-isolated PV grid-connected inverter application. In this paper,an novel DC component suppression strategy was proposed based on an improved PCI controller. Firstly,considering the DC component as system disturbance,a disturbance observer（DOB） was designed to observe the system’s DC component in real-time,then a compensation method was designed for suppressing DC component based on the observed value of DC component. Secondly,a resonance complex coefficient PCI controller was substitute for the traditional PCI controller to obtain more phase margin. Finally,the feasibility and validity of the proposed strategy were verified by the simulation and experimental results.