In　order　to　investigate　the　transmission　efficiency　of　movable-teeth　CVT　(MCVT),　the　power　losses　of　MCVT　was　analyzed　and　the　theoretical　model　of　its　transmission　efficiency　was　set　up.　Then,　transmission　efficiency　test　platform　was　set　up　for　the　MCVT.　Lastly,　experimental　study　of　the　relations　among　transmission　efficiency,　speed　and　torque　was　conducted　when　the　transmission　ratio　was　fixed.　The　results　show　that　the　power　losses　of　the　sliding　friction　and　impact　caused　by　the　backlash　of　the　tooth,　the　power　loss　of　the　oil　stirring　and　the　power　loss　of　oil　seal　are　the　main　power　losses　of　iMCVT.　The　transmission　efficiency　of　iMCVT　can　reach　95%　when　the　constant　transmission　ratio　is　1.2.Torque　is　the　most　significant　impact　to　the　transmission　efficiency.　The　effect　of　speed　on　the　transmission　efficiency　of　iMCVT　is　not　significant,　but　the　efficiency　of　high　speed　is　greater　than　that　of　low　speed.　The　transmission　efficiency　is　gradually　increasing　when　speed　and　torque　both　range　from　the　low　to　high.　©　2016,　Editorial　Department　of　Journal　of　Beijing　University　of　Technology.　All　right　reserved.