Abstract: A series of boundary layer transition measurements of the 7° half angle cone at Mach 6 in the Aero-physic Range were conducted. The models are made of aluminum alloy with black oxidation or low thermal conductivity coating. The base diameter of the cone is 33mm, and the radius of the nose tip is among 0.27~2.50mm. The parameter covers Mach number 4.89~6.63, Unit Reynolds number 4.8×10⁷/m~5.2×10⁷/m, and the total angle of attack 0.8°~5.8°. The boundary layer shadowgraph and surface inferred images which reflect the transition line configuration were obtained, and the transition Reynolds number was calculated to be 2.4×10⁶~5.6×10⁶. The results indicate that:the transition Reynolds number decreases by enlarging the angle of attack, certain nose tip scale would delay the transition.