CaDyAlO4　(CDA)　crystals　with　dimensions　of　Phi　25　x　28　mm3　were　grown　by　the　Czochralski　method.　The　presence　of　a　small　amount　of　oxygen　in　the　growth　atmosphere　will　cause　the　coloration　of　CDA　crystal,　and　correspondingly　reduce　the　transmittance　in　the　range　of　400-730　nm.　Rietveld　structural　refinement　of　XRD　patterns　revealed　a　slight　difference　in　the　unit　cell　parameters　of　the　brown　and　yellow-green　CDA　crystals.　The　angular　and　temperature　dependencies　of　the　magnetic　susceptibility　were　measured,　indicating　that　CDA　crystal　has　remarkable　magnetic　anisotropy　and　abnormal　magnetic　behavior　in　the　a　and　c　direction　below　150　K.　Faraday　rotation　characteristics　of　CDA　crystal　were　investigated　at　room　temperature.　Verdet　constant　of　CDA　at　500-700　nm　band　is　about　1.1　times　as　large　as　that　of　TGG,　but　only　0.69　fold　of　that　for　isostructural　CaTbAlO4　(CTA).　Based　on　the　Van　Vleck-Hebb　theory,　the　effective　transition　wavelength　and　probability　of　three　crystals　were　calculated　and　compared.　The　absorption　and　magnetic　circular　dichroism　spectra　(MCD)　of　4f-4f　transitions　in　Dy3+　ions　in　CDA　were　studied.