Janus　nanoparticles　(JNPs)　have　drawn　significant　attention　due　to　their　unique　surfaces　with　dual　character.　Herein,　molecular　dynamics　simulation　was　conducted　to　investigate　the　molecular　transfer　characteristics　across　the　hexane/water　interface　with　amphiphilic　JNPs,　to　elucidate　the　interfacial　mass　transfer　enhancement　mechanisms.　The　results　manifested　that　the　enhancement　by　JNPs　first　increases　and　then　decreases　with　the　rise　of　alkyl　chain　length,　which　is　up　to　the　biggest　improvement　under　the　C4H9　alkyl　chain　(JNPs-4).　The　enhancement　can　be　ascribed　to　the　competitive　balance　between　solute　diffusion　behaviors　and　molecule　interaction　energy.　The　self-diffusion　coefficient　of　solute　and　the　interaction　between　the　solute　and　oil　phases　decreases,　while　the　interaction　between　the　solute　and　water　phases　increases　with　the　rise　of　alky　chain　length.　Moreover,　maximum　enhancement　can　be　obtained　by　5　vol%　concentration　JNPs-4　with　13.4　angstrom　particle　diameter,　in　which　the　mass　transfer　resistance　is　reduced　by　36.8%.　(C)　2021　Elsevier　Ltd.　All　rights　reserved.