To　solve　high　power　consumption　and　problem　of　braking　torque　heat-fade　of　the　conventional　eddy　current　brake,　a　new　active　electromagnetic　liquid-cooled　retarder　was　proposed　based　on　the　principle　of　eddy　current　brake　and　motor　energy　regeneration　brake.　The　new　type　of　retarder　included　a　liquid　cooled　eddy　current　retarder　and　a　single-phase　switched　reluctance　motor　with　an　outer　rotor.　The　mathematical　model　of　electromagnetic　field　for　the　retarder　was　established.　The　braking　performance　of　the　retarder　was　predicted　by　numerical　simulation,　the　opening　and　closing　angle　of　the　switched　reluctance　motor　were　optimized,　and　the　energy　recovery　power　of　the　the　switched　reluctance　motor　in　the　downhill　continuous　braking,　the　energy　recovered　in　the　emergency　braking　and　start　torque　at　low　speed　were　calculated.　At　last,　tests　for　the　air　loss　moment,　heat-fade　of　braking　toque,　power　generation　performance　and　power-driven　performance　were　carried　out.　The　test　results　showed　that　the　eddy　current　braking　torque　reached　1　260　N•m　at　1　000　r/min.　The　braking　torque　was　declined　by　15%　in　the　continuous　braking　stage.　The　braking　torque　of　the　motor　was　increased　at　first　and　then　decreased　with　the　increase　of　speed.　When　the　speed　was　1　000　r/min,　the　braking　torque　of　the　motor　reached　the　maximum;　when　the　vehicle　was　slowed　down　at　speed　of　35　km/h,　the　recovery　power　was　up　to　94　kW.　©　2018,　Chinese　Society　of　Agricultural　Machinery.　All　right　reserved.