Islanding detection is an essential part of the grid-connected DG system. To implement a fast, convenient and economical islanding detection scheme, and meanwhile to minimize the impact of islanding detection on power quality, a new islanding detection method based on the short-filtering devices is proposed. To begin with, this paper makes a brief introduction to LCL filter device’s parameter design. And then, the principle of this islanding detection scheme is described, which specifically involves the use of short-filtering device and the detection of the change of voltage harmonic injected into the system by DG to calculate the voltage total harmonic distortion rate at the point of common coupling (PCC) and thus whether an islanding state occurs is determined. The advantages of this method include easy achievements and the feasibility of the convenient and rapid islanding detection. And moreover it can be achieved by the simple transformation of inverter and brings simultaneous cost reduction. Simulation and experimental results verify that the method is effective and feasible.