How to substract the background clutter accurately has always been an important research for many years because it is a major factor influencing the RCS measurement. A traditional method to substract the clutter is based on a fact that if the dihedral rotating angle (around the radar line of sight (LOS)) is an integer multiple of 180°, the mathematic expectation of the dihedral signal samples equals zero. However, the algorithm proposed in this paper can get higher accuracy, which is the combination of Hyper Circle and LMS algorithm. What’s more, averaging the sum of four channels gets better results which are superior to any single channel results. Numerical simulation demonstrates the excellent performance of the proposed technique.