We investigated the characteristics of hollow cathode discharge（HCD） and the scattering of electromagnetic wave on HCD plasmas. The volt-ampere characteristic curves of rectangular and column HCDs were measured experimentally and the plasma density was obtained by using the method of microwave measurement. Moreover

we investigated the transmission coefficients of electromagnetic wave interacting with several kinds of plasmas. The results show that HCD can generate high-density plasma density depending on the discharge current. A sheet HCD plasma can sufficiently block x-band microwaves. The plasma column of cylindrical HCD can scatter the electromagnetic wave to the lateral directions

with the peaks at an angle of ±15°. The peak value increases with the discharge current（or plasma density）. A well-arranged plasma array can act as planar plasma when acting with electromagnetic waves.