Supercritical　carbon　dioxide　printed　circuit　board　heat　exchangers　are　expected　to　be　applied　in　third-generation　solar　thermal　power　generation.　However,　the　uniformity　of　supercritical　carbon　dioxide　entering　the　heat　exchanger　has　a　significant　impact　on　the　overall　performance　of　the　heat　exchanger.　In　order　to　improve　the　uniformity　of　flow　distribution　in　the　inlet　header.　This　article　studies　and　optimizes　the　inlet　header　of　a　printed　circuit　board　heat　exchanger　through　numerical　simulation.　The　results　indicate　that　when　supercritical　carbon　dioxide　flows　through　the　header　cavity,　eddy　currents　will　be　generated,　which　will　increase　the　uneven　distribution　of　flow　rate,　while　reducing　the　generation　of　eddy　currents　will　improve　the　uniform　distribution　of　flow　rate.　When　the　dimensionless　factor　of　the　inlet　header　is　6,　the　hyperbolic　configuration　is　the　optimal　structure.　We　also　reduced　the　eddy　current　region　by　adding　transition　segments,　and　the　results　showed　that　the　structure　was　the　best　when　the　dilation　angle　was　10　degrees,　which　reduced　the　non-uniformity　by　21%　compared　to　the　hyperbolic　configuration,　providing　guidance　for　engineering　practice.