The　eddy　current　braking　(ECB)　is　often　installed　on　heavy-duty　vehicles　as　the　auxiliary　braking　component.　When　it　works　for　a　long　time,　the　thermal　derating　of　braking　torque　will　reach　about　18.5　%　due　to　high　temperature.　It　is　important　to　establish　an　accurate　magneto-thermal　coupling　model　for　the　ECB　high-temperature　steady-state　braking　torque　prediction.　In　multi-field　coupling　calculation,　there　are　two　commonly　used　data　transmission　methods　between　two　physics　fields.　One　of　them　is　transmitting　average　data　to　important　geometry　based　on　the　idea　of　lumped　parameters　(lumped　parameters　method),　and　the　other　is　mapping　the　data　distribution　to　each　grid　cell　(direct　mapping　method).　This　paper　takes　the　ECB　as　the　research　object,　analyzes　the　influence　of　the　above　two　data　transmission　methods,　and　proposes　to　replace　the　fluid-thermal　coupling　model　with　the　heat　conduction　model　in　the　magneto-thermal　coupling　model.　Through　calculation　and　analysis,　using　the　lumped　parameters　method　to　transmit　the　heat　generation　rate,　temperature　and　convective　heat　transfer　coefficient　all　have　a　certain　impact　on　the　calculation　accuracy　of　the　coupling　model　comparing　with　the　direct　mapping　method.