Based on the electromagnetic properties of complementary split ring resonator (CSRR), a novel artificial magnetic conductor (AMC), CSRR-AMC, is designed. The comparison of the reflection phase with square patch AMC reveals its features of miniaturization and multiband in-phase reflection, under X- and Y-polarized normal incident waves, respectively. Inspired by the reflection phase difference under different incident conditions, we have designed a wideband low rader cross-section (RCS) reflection screen with a single CSRR-AMC structure. The CSRR-AMC arrays are orthogonally positioned and the backscattering energy is reduced as a result of phase cancellation. Measured results demonstrate that -10dB RCS reduction is achieved in a wide frequency range of 7.38–10.47 GHz and the relative bandwidth is 34.6%, providing a new method for the design of wideband low scattering structure.