On　the　basis　of　density　functional　theory　calculations,　we　study　the　electronic　and　magnetic　properties　of　an　iron　phthalocyanine　(FePc)　nanosheet　(FePcNST)　and　its　derivatives,　nanoribbons　(FePcNRs)　and　nanotubes　(FePcNTs).　The　GGA+U+SOC　calculations　reveal　that　the　interesting　in-plane　magnetic　anisotropy　comes　from　unquenched　in-plane　orbital　moments　for　FePcNST.　The　calculations　indicate　that　the　most　stable　antiferromagnetic　(AFM)　ordering　for　FePcNRs　is　G-type　AFM,　which　is　independent　of　the　ribbon　width.　In　addition,　FePcNTs　with　radii　larger　than　10　A　are　thermodynamically　and　thermally　stable　and　can　be　rolled　up　from　the　FePcNST　with　only　several　millielectronvolts　energy　cost.　Interestingly,　the　most　stable　AFM　types　of　FePcNTs　highly　depend　on　the　number　of　Fe　ions　(odd　or　even)　on　the　circumference.　These　results　may　shed　useful　light　on　further　experimental　and　theoretical　studies　on　the　organometallic　nanosheet　and　its　one-dimensional　derivatives.　©　2012　American　Chemical　Society.