This work deals with how to use suitable formula of convective heat transfer coefficient in order to exactly calculate aerodynamic heating in high speed laminar flow over a flat plate. One formula of convective heat transfer coefficient of hypersonic flow was developed by modified Reynolds analogy, using reference temperature or reference enthalpy. The formula was checked basing on the Blasius similar solution of compressible flow. Due to similar solutions still exists in flat hypersonic boundary layer flow for variable specific heat, which is real gas effect resulting of high temperature, the heat flux could be calculated at isothermal wall condition and thus the convective heat transfer coefficient. In this paper, the computation is conducted in the flat hypersonic boundary layer flow, under isothermal condition with wall temperature ranging from 0.1 to 0.9 times the adiabatic temperatures, incoming flow Mach number 1 to 10. Both the results by the formula using reference enthalpy and that using Fourier's Law by Blasius solution of considering real gas effect are good agreement with each other, and the maximum relative error being less than 3%, which is much better than that by using reference temperature one. In addition, the formula was applied to real computation of supersonic flow passing one meter long flat plate with the wall being convective heat transfer. The time needed and wall temperature rising rule are studied for the wall temperature from the initial temperature to 0.9 times adiabatic temperature. The results indicated that whether isothermal or adiabatic condition in hypersonic flow chosen as the wall boundary condition is not suitable in real flow especially during the very long period flying. (C) 2017 Elsevier Ltd. All rights reserved.