Miniaturization　and　integration　in　electronic　devices　have　caused　a　rapid　increase　in　heat　flux.　Dissipation　of　high　heat　flux　from　devices　for　uniform　temperature　is　essentially　required　to　ensure　device　safety.　Therefore,　a　variable-period　sinusoidal　microchannel　heat　sink　is　proposed　to　enhance　heat　transfer　and　improve　the　uniformity　of　temperature　distribution.　Experimental　and　numerical　simulation　methods　are　adopted　to　investigate　the　single-phase　heat　transfer　performance　of　deionized　water　under　different　heat　fluxes　and　flow　rates.　The　temperature,　Nusselt　number,　pressure　drop,　thermal　resistance,　pumping　power,　and　temperature　and　flow　field　distribution　of　the　variable-period　sinusoidal　microchannel　heat　sink　are　obtained　and　compared　with　those　of　a　traditional　sinusoidal　microchannel　heat　sink.　Results　show　that　the　variable-period　sinusoidal　microchannel　improves　fluid　disturbance　and　heat　transfer　area　to　enhance　heat　transfer　but　increases　flow　resistance.　The　maximum　temperature　difference　is　reduced　by　2.3-3.5　K,　and　the　Nusselt　number　is　improved　by　13.1　%-7.8　%,　albeit　with　increasing　pressure　drop　by　about　7.5　kPa.　The　uniformity　of　temperature　distribution　is　improved　by　8.5　%-32.9　%.　Under　the　same　pumping　power,　the　average　reduction　in　thermal　resistance　is　about　13　%.　And　under　the　same　thermal　resistance,　the　average　reduction　in　pumping　power　is　about　70.　These　results　demonstrate　that　the　variable-period　sinusoidal　microchannel　can　improve　the　overall　thermohydraulic　performance　of　the　heat　sink.