The　electromagnetic　induction　phenomena　of　nitrogen-ferrofluid　two-phase　flow　based　on　the　magnetic　permeability　differences　between　ferrofluids　and　non-magnetic　bubbles　were　studied　theoretically　and　experimentally.　Water-based　Fe3O4ferrofluids　with　particle　volumetric　concentration　of　3.83%　were　filled　in　a　vertical　tube,　and　a　visual　observation　was　performed　using　water,　whose　properties　are　similar　to　the　ferrofluids　under　study.　The　results　show　that　the　electromotive　force,　being　of　the　order　of　a　few　millivolts,　would　be　induced　in　the　cases　of　bubbly　flow,　slug　flow　and　churn　flow.　The　peak-to-peak　value　of　induced　electromotive　force　increases　with　an　increase　in　the　volumetric　flux　of　gaseous　phase.　In　addition,　the　flow　regimes　can　be　discriminated　by　the　waveforms　of　induced　electromotive　forces.