This　study　deals　with　the　influence　of　high　concentration　and　high　dispersion　nanodots　in　toluene-based　fluids　on　the　improvement　of　the　thermal　conductivity　of　ZrO2/toluene　nanofluids　by　experimental　measurement　and　theoretical　analysis.　For　this　purpose,　the　high　concentration　(13.21　vol%)　ZrO2/toluene　nanofluids　were　diluted　to　2.20%,　4.41%,　6.61%,　8.81%　and　11.01%,　respectively.　And　their　thermal　conductivities　were　measured　using　the　transient　planar　heat　source　method　(TPHS).　Subsequently,　the　predicted　values　of　four　classical　theoretical　models　were　compared　and　discussed　with　experimental　values　in　detail　to　verify　the　applicability　of　theoretical　models.　The　results　indicate　that　almost　all　of　the　thermal　conductivities　of　ZrO2/toluene　nanofluids　are　higher　than　that　of　the　pure　toluene　fluid,　and　the　trend　is　rising　with　the　increase　in　temperature.　Moreover,　the　thermal　conductivity　enhancement　of　ZrO2/toluene　nanofluid　with　13.21　vol%　has　achieved　38.7%　and　59.9%　at　room　temperature　and　62.8　°C,　respectively.　The　visualized　behaviors　of　nanodots,　including　migration,　collision,　energy　exchange　between　the　nanodots　reveal　the　physical　mechanism　that　contributes　to　the　thermal　conductivity　of　nanofluids.　And　the　thermal　conductivity　enhancement　of　nanofluid　per　unit　concentration　quantifies　the　mechanism.　The　Brownian　motion　of　nanodots　may　play　a　crucial　role,　which　influences　the　move,　collision,　and　micro-convection.　The　predicted　values　of　four　models　were　compared　and　discussed　with　experimental　values　to　verify　the　applicability　of　theoretical　models.　The　analysis　reveals　that　all　predicted　values　are　closer　to　experimental　results　at　low　temperatures.　Compared　with　other　models,　the　thermal　conductivity　value　predicted　by　the　Shukla　model　is　closer　to　the　experimental　value　at　middle　and　high　temperatures.　In　this　work,　the　thermal　conductivity　of　ZrO2/toluene　nanofluids　has　been　greatly　improved,　which　has　shown　its　promising　applicability　in　thermal　management　in　practical　engineering　applications.　©　2022