Laser-metal　inert　gas　(MIG)　hybrid　welding　has　been　recently　suggested　as　a　feasible　process　for　joining　of　steels　to　Al　alloys　for　structural　applications.　In　the　present　study,　keyhole　laser-MIG　hybrid　welding　and　laser-MIG　hybrid　welding-brazing　processes　were　performed　to　join　6　mm　thick　Q235　steels　and　5083　Al　alloy　plates.　Effects　of　laser-MIG　hybrid　process　parameters　on　the　bead　appearance,　weld　shape,　interface　microstructures,　and　microhardness　of　the　steel/Al　alloy　butt　joints　were　investigated.　Research　results　show　that　a　soundly　joined　steel/Al　alloy　butt　joint　had　been　achieved　by　using　two　keyhole　laser-MIG　hybrid　welding　processes.　However,　two　laser-MIG　hybrid　processes　had　obvious　different　influence　on　the　morphology,　thickness,　and　hardness　of　the　intermetallic　compound　(IMC)　layer　at　the　interface.　The　IMC　layers　at　the　interface　produced　by　keyhole　laser-MIG　hybrid　welding　were　mainly　composed　of　the　Fe2Al5　and　the　Fe4Al13　phases,　whereas　a　new　Fe2Al8Si　phase　was　formed　at　the　interface　of　the　joints　produced　by　keyhole　laser-MIG　hybrid　welding-brazing　process　with　Al-Si　filler　wires,　which　led　to　a　decrease　of　the　microhardness　from　898.8　to　620.0　HV　at　the　interface.　Therefore,　it　demonstrates　that　MIG　laser-MIG　hybrid　welding-brazing　process　was　of　considerable　improvement　of　the　brittleness　of　the　interface　of　the　steel/Al　alloy　butt　joints.　(C)　2018　Laser　Institute　of　America.