Abstract: In the structural heat protection design for hypersonic vehicles, a CFD software is often used to obtain the heat flow data at the nodes of the aerodynamic grid, while another grid system, the structure grid is used for the design of the thermal protection tiles. The number of nodes and the node positions for the two grid systems are often different that it is necessary to transfer the heat flow load data from the source grid to the target one. In addition, the time-variant heat flow with regard to one specific part of the aircraft is also different for different flight orbits. In order to determine the thickness of the protection tile under the requirements of all orbit conditions, an envelope curve representing the most severe heat flow profile is needed to be imposed on each structural grid point. In this paper, by improving the constant volume transformation (CVT) method, the calculating efficiency for the heat flow transferring is enhanced. A new method for fitting the envelope load curve is proposed. The results of examples show that the calculation efficiency is enhanced and the preprocessing of the data is significantly simplified.