Magnetic　fluids,　a　new　type　of　energy　transfer　fluid　with　tunable　properties,　have　garnered　significant　interest　from　researchers　worldwide.　Hybrid　magnetic　fluids　prepared　by　adding　different　types　of　nanoparticles　exhibit　superior　thermophysical　properties　and　functional　characteristics.　In　this　paper,　we　prepared　a　water-based　magnetic　fluid　loaded　with　multi-walled　carbon　nanotubes　(MCNTs),　silver　(Ag),　and　copper　(Cu)　to　enhance　thermal　conductivity.　Using　a　transient　double　hot-wire　method,　we　designed　and　built　an　experimental　measurement　system　for　the　thermal　conductivity　of　magnetic　fluids　with　an　average　measurement　error　of　less　than　5%.　We　studied　the　thermal　conductivity　of　hybrid　magnetic　fluids　under　different　conditions　and　evaluated　the　advantages　and　disadvantages　of　various　models,　including　the　Maxwell　model,　H&C　model,　Tim　model,　Y&C　model,　and　Evans　model.　Our　results　show　that　MF+MCNTs,　MF+Ag,　and　MF+Cu　nanofluids　can　all　improve　the　thermal　conductivity　of　the　carrier　fluid,　with　MF+MCNTs　exhibiting　the　best　improvement　effect　of　10.93%.　Among　the　five　models　evaluated,　the　Evans　model　had　the　best　predictive　effect　with　a　deviation　range　within　5%.　This　work　provides　theoretical　and　practical　reference　for　enhancing　the　thermal　conductivity　of　magnetic　fluids　and　provides　a　more　accurate　theoretical　model　for　calculating　the　thermal　conductivity　of　hybrid　magnetic　fluids.