In　this　paper,　a　three-dimensional　CFD　numerical　model　of　heat　transfer　and　fluid　flow　was　developed　to　simulate　the　thermal　performance　of　the　novel　flat　plate　solar　collector　based　on　a　micro　heat　pipe　array　to　provide　a　theoretical　basis　for　the　structure　improvement　and　optimization　of　the　collector.　The　simulation　of　the　novel　collector　with　water　flow　included　the　CFD　modeling　of　solar　irradiation　and　the　modes　of　mixed　convection　and　radiation　heat　transfer　between　the　absorber　plate　and　glass　cover,　as　well　as　the　heat　transfer　in　the　circulating　water　inside　the　heat　exchanger　and　conduction　of　the　insulation.　The　fluid　flow　and　heat　transfer　in　the　computational　domain　satisfied　the　continuity　equation,　the　momentum　equation,　and　the　energy　equation.　The　standard　k-Ε　two-equation　turbulence　model　was　used　in　this　paper.　In　order　to　predict　the　direct　illumination　energy　source　that　results　from　incident　solar　radiation　and　the　radiation　field　inside　the　collector,　the　discrete　ordinate　radiation　model　with　a　solar　ray-tracing　model　was　used.　A　commercial　computational　fluid　dynamics　program　(Fluent　6.3　CFD　software)　was　used　to　solve　the　coupled　fluid　flow,　heat　transfer,　and　the　radiation　equation.　The　solver　used　is　the　segregated　solver.　Body　Force　Weighted　was　selected　as　the　discretization　method　for　pressure,　and　the　SIMPLE　algorithm　was　used　to　resolve　the　coupling　between　pressure　and　velocity.　The　discretization　methods　for　the　solving　of　momentum,　energy,　radiation,　and　turbulence　were　second　order　upwind.　The　thermal　performance　could　be　achieved　by　simulation　results　under　different　conditions.　Then,　the　experimental　and　numerical　results　were　compared　to　validate　the　prediction　of　the　CFD　model.　The　results　showed　that　the　numerical　results　of　the　thermal　efficiency　of　the　novel　collector　were　in　reasonable　agreement　with　the　experimental　data.　The　validated　CFD　model　was　used　to　analyze　the　properties　of　the　insulation　layer.　First,　the　effects　of　the　thickness　of　solid　insulation　on　the　thermal　performance　of　the　collector　were　simulated　using　the　numerical　model.　It　indicated　that　when　the　thickness　of　solid　insulation　was　0.02,　0.03,　0.04,　and　0.05　W/(m·K)　respectively,　the　optimum　thickness　of　solid　insulation　was　respectively　4.5,　5.0,　5.5,　and　5.5　cm　respectively.　Then,　in　order　to　save　cost,　a　new　concept　of　the　hollow　insulation　was　presented　on　the　insulation　design　of　the　collector,　namely　the　combination　of　an　air　layer　and　a　solid　insulation　layer.　The　simulations　were　conducted　for　the　collector　with　a　different　size　of　the　hollow　insulation.　The　thermal　efficiency　comparison　results　of　the　collector　for　the　hollow　insulation　and　the　solid　insulation　resulted　in　the　following　conclusions:　1)　When　the　thickness　of　insulation　was　4cm,　the　collector　of　hollow　insulation　with　combination　of　2　cm　air　layer　and　2　cm　solid　insulation　could　get　the　same　thermal　performance　as　the　solid　insulation.　And　25%-50%　of　the　cost　and　weight　of　the　insulation　were　saved.　2)　When　the　thickness　of　insulation　was　5cm,　the　collector　of　hollow　insulation　with　combination　of　2　cm　air　layer　and　3　cm　solid　insulation　could　get　the　same　thermal　performance　as　the　solid　insulation.　And　nearly　40%　of　the　cost　and　weight　of　the　collector　were　saved.　3)　When　the　thickness　of　insulation　was　6cm,　the　collector　of　hollow　insulation　with　combination　of　3　cm　air　layer　and　3　cm　solid　insulation　could　get　the　same　thermal　performance　as　the　solid　insulation.　Nearly　50%　of　the　cost　and　weight　of　the　insulation　were　saved.　Therefore,　a　reasonable　design　of　the　hollow　insulation　could　obtain　the　same　resemblance　thermal　insulation　effect　as　the　solid　insulation　collector,　but　the　cost　and　weight　could　decrease　from　25%-50%.　©,　2015,　Chinese　Society　of　Agricultural　Engineering.　All　right　reserved.