In　this　paper,　the　absorbing　effectiveness　of　spherical　particle　absorber　made　of　cheap　Fe-rich　hollow　cenosphere　fly-ash　is　analyzed.　The　effects　of　the　diameter　of　spheres,　the　number　of　layer　and　the　stack　modes　of　sphere　particle　on　the　absorbing　effectiveness　were　explored.　Based　on　the　results,　a　three-layer　structure　with　mixed　sizes　of　spheres　was　designed,　constructed　and　tested.　Obtained　results　show　that　this　structure　has　a　maximal　reflection　loss　of　9　dB　and　the　bandwidth　being　higher　than　5　dB　is　more　than　17　GHz.　When　applying　the　permittivity　of　Fe-rich　hollow　cenosphere　fly-ash,　and　the　thickness　of　absorber　is　6.5　cm,　the　maximal　reflection　loss　is　23　dB　and　the　bandwidth　being　lower　than　-10　dB　is　more　than　14　GHz,　which　covers　the　C,　X　and　Ku　bands.　The　experimental　test　proved　that　the　three-layer　structure　absorber　has　good　absorbing　effectiveness.