Aiming　at　slippage　and　belt　breakage　of　large　mechanical　conveyor　belts,　a　new　type　of　water-cooled　permanent　magnet　brake　(WPMB)　is　proposed.　In　order　to　determine　the　braking　performance　of　WPMB,　a　multi-physics　coupling　model　and　analysis　method　of　magneto-thermal-structure　are　built.　The　braking　torque　and　temperature　characteristics　of　WPMB　under　different　working　conditions　are　obtained.　Based　on　the　magnetic　vector　potential　equation,　an　electromagnetic　eddy　current　model　is　established,　and　the　variation　trend　of　braking　torque　with　speed　is　predicted.　The　temperature　field　model　is　built　based　on　the　equivalent　thermal　network　method.　Using　multi-field　coupling　analysis　method　and　3-D　FEM,　the　influence　factors　of　WPMB　braking　torque　are　analyzed.　Two　test　prototypes　with　rated　speed　of　78　rpm,　braking　torque　of　3000　N　center　dot　m　are　designed　and　developed.　Braking　torque　characteristic　tests　and　magnetic　shielding　characteristic　tests　at　different　speeds　and　continuous　braking　characteristic　test　are　carried　out.　Experiments　show　that　the　proposed　method　provides　very　practical　results　to　ensure　the　continuous　and　stable　operation　of　WPMB.