A　new　selenite　compound　CdNi(SeO3)(2)(H2O)(2)　has　been　obtained　by　a　conventional　hydrothermal　method.　This　compound　crystallizes　in　monoclinic　system　of　space　group　C2/c,　which　exhibits　a　layer　structure　built　by　NiO6　octahedra　and　SeO3　trigonal　pyramids　running　along　the　a-axis.　The　layers　show　a　unique　eight-rings　hole　network.　The　compound　is　stable　at　room　temperature　while　the　loss　of　H2O　molecules　happens　with　heating　above　523　K.　Magnetic　measurements　indicate　that　CdNi(SeO3)(2)(H2O)(2)　is　an　antiferromagnet　and　possesses　an　antiferromagnetic　ordering　at　T-N　=　15　K.