Effective　energy　storage　and　conversion　technologies　have　attracted　extensive　attention　for　developing　advanced　rechargeable　batteries.　The　high-energy　capacity　of　molybdenum　disulfide　(MoS2)　monolayer　for　Li-ion　battery　was　recently　introduced.　Compared　with　Li-ion　battery,　the　growing　interests　have　been　concentrated　on　the　Na-ion　batteries　and　Mg-ion　batteries　based　on　two-dimensional　nanomaterials.　Though　the　Li-　and　Mg-ion　batteries　based　on　MoS2　nano-tubes　have　been　theoretically　studied,　knowledge　about　the　Na,　Mg　ion　batteries　with　MoS2　monolayer　is　lack　To　look　insight　into　the　capability　of　energy　storage,　herein,　we　performed　the　first-principles　calculations　to　investigate　the　Li,　Na,　and　Mg　ions　adsorption　on　and　diffusion　through　the　MoS2　monolayer.　The　binding　energies　of　these　ions　at　different　sites,　including　top　of　S　atom,　top　of　Mo　atom,　and　hole　site　(centre　of　hexagonal　lattice),　were　measured.　It　was　found　that　the　binding　energy　at　the　top　of　Mo　atom　is　the　largest,　which　indicates　the　possibly　stable　absorption　configuration.　Energy　barriers　of　ions　passing　through　and　diffusing　over　the　MoS2　monolayer　were　also　calculated.　Results　show　that　the　Mg-ion　has　a　largest　energy　barrier　to　pass　through　the　MoS2　layer　and　a　smallest　energy　barrier　to　diffuse　above　the　MoS2　layer.　The　band　structures　and　density　of　states　of　MoS2　before　and　after　ion　absorption　were　also　calculated　and　discussed.