Abstract: For the long time steady measurement of heat flux of MW magnitude, a calorimetric heat-flux sensor of new structure is designed based on the boiling heat transfer method. A U-shaped water cooling channel is designed, with expected measuremente range from 5 to 15 MW/m². The sensor is tested in the high temperature supersonic gas flow field, to find its real range of 3 to 25 MW/m². It is shown that the application of the boiling heat transfer method makes the design much easier due to the better heat transfer efficiency at a lower speed and a smaller pressure loss of the subcooled water, leading to its extended range for measurment.