The　excellent　thermal　conductivity　of　the　carbon　nanotubes　leads　to　the　high　thermal　conductivity　of　the　nanofluids　prepared　by　carbon　nanotubes.　The　addition　of　functional　groups　on　the　surface　of　the　carbon　nanotubes　canimprove　the　stability　of　the　water/CNT　nanofluids.　The　excellent　diffusion　properties　of　the　Janus　particles　result　in　the　elevated　thermal　conductivity　of　the　Janus　nanofluids.　In　thiswork,　hydroxylated　single-walled　carbon　nanotube　(SWCNT-OH)　particles,　as　Janus　particles,　are　constructed　and　a　water/SWCNT-OH-Janus　nanofluid　model　is　proposed　by　introducing　SWCNT-OH　particles　into　a　base　fluid　(water).　By　using　equilibrium　molecular　dynamics　simulations,　the　thermal　conductivity　of　nanofluids　is　calculated.　The　mechanism　of　the　enhanced　thermal　conductivity　is　investigated　by　analyzing　the　solid-like　liquid　layers　formed　by　liquid　molecules　around　particles,　Brownian　motion　of　CNT　particles,　and　CNT/water　interfacial　thermal　resistance.　It　can　be　concluded　that　the　thermal　conductivity　of　the　nanofluids　with　SWCNT-OH　particles　can　be　enhanced　compared　with　that　of　the　nanofluids　with　normal　SWCNT　particles.　The　hydrogen　bond　between　hydroxyl　group　and　water　molecules　results　in　the　adsorption　of　water　molecules　onto　the　surface　of　carbon　nanotube.　This　process　increases　the　density　of　the　liquid　adsorption　layer　on　the　CNT　surface,　thereby　enhancing　the　effect　of　the　solid-　liquid　layer.　The　hydroxyl　groups　on　the　CNT　surface　degrade　the　solid-liquid　interfacial　thermal　resistance,　which　promotes　the　heat　transfer　within　the　nanofluids.　Moreover,　the　hydroxyl　groups　also　enhance　the　interaction　between　the　CNT　particles　and　the　water　molecules,leading　to　stronger　Brownian　motionof　particles.　The　combination　of　these　factors　will　be　responsible　for　the　enhancement　thermal　conductivity　of　the　water/SWCNT-OH　nanofluids.For　SWCNT-OHJanus　nanofluids,　the　thermal　conductivity　can　be　further　enhanced,　owing　to　the　strong　Brownian　motion　of　the　Janus　particles.