According　to　the　different　cooling　medium,　the　electric　motor　cooling　styles　can　be　divided　into　liquid　cooling　and　air　cooling;　the　former　involves　water　cooling　and　oil　cooling　while　the　latter　comprises　natural　air　cooling　and　forced　air　cooling.　Whereas,　the　air　cooling　system　is　difficult　to　meet　various　performance　requirements　for　the　modern　Electric　Vehicle　(EV).　Therefore,　approximately　all　EV　motors　are　liquid　cooled　at　present.　Moreover　with　the　trend　of　EV　motors　to　Permanent　Magnet　(PM)　and　to　high　speed,　for　instance,　the　maximum　working　rotated　speed　from　10,000rpm　to　20,000　rpm,　the　packaging　of　the　motor　is　minimized　at　same　power　while　efficiency　drops,　lifetime　shorten　and　even　cause　demagnetization　due　to　thermal　effects　without　optimum　design.　Consequently,　the　improvement　of　the　liquid　cooling　system　is　essential　to　enhance　the　efficiency　of　the　EV　motor　in　the　future　for　higher　power　density.　In　this　perspective,　the　innovative　cooling　topologies　of　electric　machines　based　on　the　development　results　of　the　parts　such　as　lubricating　oil　and　motive　seal　of　electric　vehicles　are　presented　in　this　paper.　It　solves　some　problems　brought　about　by　predecessors　in　view　of　the　high　efficiency　and　reliability　of　the　motor　with　higher　energy　density.