Abstract: A new structural unit was designed and manufactured based on the improvements to traditional frequency selective surface（FSS）of the square ring structure. Measured results and simulation results by Ansoft HFSS have shown that the frequency selectivity of the new structure units is better than the traditional one. By zigzag line design and added vertical branches，the size of the entire structure of the new unit reduced to 28.6%，which is very useful for miniaturization design of the FSS. Meanwhile，under different incident conditions，the resonant frequency drift of the new unit is around 0.04 GHz，and a higher angular stability and polarization stability are accomplished.