In this paper, a numerical analysis coupling heat transfers of the combustor internal flow, the coolant flow and the strut wall is developed and applied for the optimization of strut cooling using aviation kerosene as coolant at flow conditions corresponding to the combustor entrance condition for Mach 6 scramjet flight. The coupling procedure is tested and proven to be an efficient method of being capable to obtain the converged temperature and heat transfer solutions of the cooled strut within a few iteration steps. Four cooling designs with varied diameter, length and position of the cooling channels are investigated and their improvements on fuel injection and mixing are also verified compared to the wall injection. The kerosene-cooled strut (Strut4) is tested in a Mach 2.5 supersonic tunnel with inlet total temperature and total pressure of 1900K and 1.45MPa respectively for 60 seconds. The damaged part in the upper leading edge of the strut is observed, which is consistent with the result obtained by the numerical analysis.