Abstract: The flow around a blunt cone with different Mach numbers and angles of attack at 70~110 km was simulated by the unified gas kinetic scheme(UGKS). The aerodynamic characteristics were analyzed. Based on theoretical achievements of viscous interaction, the viscous interaction model of aerodynamic force coefficient was established, which associates aerodynamic characteristics with viscous interaction parameter, angle of attack and Mach number. The correction analysis and accuracy assessment of the prediction results were given. Preliminary tests show that the model prediction results are in good agreement with the UGKS results, which is significant for quickly obtaining the aerodynamic characteristics at high altitudes.