Two　dimensional　C3B　has　attracted　a　lot　of　attentions　due　to　its　graphene-like　structure.　In　this　work,　the　potential　of　monolayer　C3B　as　anode　material　of　lithium-ion　battery　are　systematically　studied　through　firstprinciples　calculations.　The　results　show　that　pristine　C3B　has　high　stiffness　(Young＇s　modulus　is　255.65　N/m),　good　binding　strength　of　Li　(-　2.55~-　2.66　eV),　high　capacity　(1139.96　mA　h/g)　and　good　electronic　(band　gap　is　0.64　eV)　and　ionic　conductivity　(diffusion　barrier　is　0.40　eV).　It　is　also　found　that　C3B-VC　and　C3B-VB　has　similar　cohesive　energy　and　formation　energy.　Interestingly,　C3B　shows　good　defect-independent　Li　migration　capability.　The　migration　barrier　of　Li　on　defect　C3B　was　affected　slightly　by　the　vacancy,　without　the　trap　of　Li.　Moreover,　the　vacancy　in　C3B　could　improve　conductivity　and　the　adsorption　ability　of　Li　without　the　sacrifice　of　migration　ability　of　Li.　These　interesting　properties　indicate　that　C3B　has　great　potential　for　the　application　of　anode　material　for　LIBs.