A　novel　microchannel　integrated　with　asymmetric　cavities　and　coaxially　water　droplet　ribs　has　been　proposed　to　improve　heat　transfer,　reduce　thermal　stress　and　understand　the　physical　mechanisms　in　this　study.　The　thermalhydraulic　performance　in　the　microchannel　was　numerically　simulated　at　the　Reynolds　number　(Re)　from　91.8　to　458.8.　It　shows　that　utilizing　the　conical　section　of　water　droplet　ribs　as　the　windward　side　enables　the　Nusselt　number　(Nu)　to　reach　14.9　at　Re　=　321.2,　while　employing　the　circular　arc　as　the　windward　side　results　in　the　Nu　reaching　12　at　the　same　Re,　which　are　2.04　and　1.64　times　that　of　the　conventional　microchannel　respectively.　The　physical　mechanisms　are　explained　according　to　the　synergistic　action　of　ribs　and　cavities　to　explain　the　heat　transfer　enhancement.　Moreover,　the　impact　of　the　rib　column　size　drc　on　the　thermal-hydraulic　performance　for　the　windward　side　the　conical　section　has　been　analyzed.　Increasing　drc　can　further　enhance　the　local　convection　heat　transfer.　Gradient　increasing　drc　along　the　flow　direction　can　reduce　the　temperature　gradient　while　the　pumping　power　is　constant.　The　temperature　standard　deviation　is　reduced　by　about　80.5%　when　the　pumping　power　is　about　0.26　W　for　the　optimized　microchannels.