Abstract: The characteristics of aerodynamic heating on tile-to-tile gaps in the flow of Mach number 6.1 with Reynolds number of 6.2×10 7/m was investigated in shock tunnel.Thermal in-sulating tiles and tile-to-tile gaps,arranged in T style and + style,were simulated on a flat plate model.Turbulent boundary layer was obtained upstream of the tile gaps by using a grit strip near the leading edge of the flat plate.Heat transfer was measured at the foward faces,side faces and the bottom surface of these gaps,and also at the tiles’surface.The effect of external flow angu-larity,gap width,gap depth and misalignment between tiles on the heating distribution in gaps was also examined.Experimental data reveal that the peak heating is most likely to appear on the gap top edges,especially on the forward face at the T-crossing,where a localized peak heating with amplitude approximately 11.6 times larger than that of the flat plate case was measured.It is also indicated that both the localized peak heating and the overall heating are reduced when the flow angle is adjusted to be 30°~60°,and are raised with the increasing gap width and tile-to-tile step height.