Unsteady　mixed　convective　heat　transfer　flow　past　an　inclined　square　cylinder　is　numerically　investigated　using　a　local　multi-quadric　radial　basis　function　(MQRBF)　interpolation.　The　blockage　parameter　(ratio　of　square　cylinder　length　d　to　height　of　the　computational　domain　H)　varies　from　0.025　to　0.2.　Air　is　considered　as　the　working　fluid　and　Prandtl　number　is　fixed　at　0.71.　Richardson　number　generally　affects　the　heat　transfer　efficiency　ranging　from　0　to　20.　Inclined　angle　of　square　cylinder　ranges　from　0°　to　45°.The　inlet　flow　is　assumed　to　be　laminar　and　uniform.　At　the　outlet　of　the　computational　domain,　a　convective　boundary　condition　is　compared　with　a　traditional　Neumann　condition.　A　study　of　the　shape　parameter　of　MQRBF　which　is　sensitive　to　the　distribution　of　inhomogeneous　supporting　nodes　is　provided.　The　representative　streamlines,　vortex　structures　and　isotherm　patterns　are　presented　and　discussed.　In　addition,　the　overall　lift　and　drag　coefficients,　average　Nusselt　number　and　Strouhal　number　for　unsteady　flow　are　analyzed　for　various　Reynolds　number　and　Richardson　number.　Copyright　©　2019　ASME.