Abstract: A metamaterial absorber is designed.composed of two metallic layers separated by a lossy dielectric spacer.The top layer consists of etched oblique cross-gap patch set in periodic pattern,whice the bottom one is solid metal.By fine adjusting geometry parameters of the structure,we can obtain a polarizationinsensitive, wide-incident-angle ultra-thin absorber which absorption is 99.1% and thickness is only 0.01λ.Through the radar cross section(RCS)analysis of the absorber, it demonstrates that the absorber owns the better characteristics of RCS reduction, and the most reduction value is up to 20 dB at the boresight direction.The experiment results have a good agreement with the simulation results,which verifies that the absorber owns the potential application in the fields of electromagnetic stealth.