In　order　to　solve　the　problem　of　unreasonable　distribution　of　braking　torque　in　the　electromagnetic　and　hydraulic　parts　of　the　electromagnetic　hydraulic　composite　retarder　(EHR),　this　paper　proposes　a　novel　axial　dual　air　gap　electromagnetic　hydraulic　composite　retarder　(DA-EHR).　The　DA-EHR　has　the　advantages　of　high　braking　torque,　small　electric　excitation,　small　air　loss,　fast　braking　torque　response　at　high　speed　adjustment　and　simple　control.　This　paper　firstly　introduces　the　structure　and　working　principle　of　the　DA-EHR.　The　influence　of　the　salient　pole　structure　on　the　braking　torque　is　analyzed　using　the　magnetic　circuit　method.　The　distribution　characteristics　of　the　transient　air　gap　magnetic　field　and　eddy　current　field　of　the　electromagnetic　part　are　obtained　using　the　3D　finite　element　method　(FEM),　and　the　pressure　field　distribution　of　the　hydraulic　part　is　also　determined.　Subsequently,　the　speed-braking　torque　characteristics　are　predicted.　Finally,　the　DA-EHR　test　prototype　of　the　same　size　is　built　and　its　braking　performance　is　obtained　through　bench　test.　The　results　show　that　compared　with　the　EHR,　the　DA-EHR　has　larger　braking　torque　and　more　reasonable　distribution　of　braking　torque.　The　electric　excitation　has　decreased　by　about　70%.　The　air　loss　of　the　hydraulic　part　has　decreased　by　about　80%.　At　2000　r/min,　the　braking　torque　of　the　DA-EHR　has　increased　by　about　13.5%.　And　the　braking　torque　of　its　electromagnetic　part　has　increased　by　about　109%.　The　adjustment　range　of　the　braking　torque　has　increased　from　31%　to　77%.　IEEE