TVD-type schemes are frequently adopted in hypersonic flowsimulation. In construction of such kind schemes, approximate Riemannsolvers are fundamental. It is investigated through analysis and numericalexamination in the present paper that how the dissipative property ofapproximate Riemann solver affects the aerodynamic heating in numericalsimulation of hypersonic flow. Numerical examples show that approximateRiemann solver severely contaminates the boundary layer resolution. If exactRiemann solver adopted, the accuracy of numerical aerodynamic heating couldbe greatly improved and the grid cell size might be coarser by a factor of10.