Abstract: This paper studies the motion characteristic of the nose cap revolving separation of the supersonic vehicle in the stiff atmosphere by the wind tunnel drop model test and acquiares the law of the centroid distance and pitch angle variance for the two part nose cap when the nose cap separate. The experiment Mach number is Ma=1.5. The study shows that when the nose cap splays out by the intrinsic constringent spring, the high dynamic pressure afflux into the antrum of the two nose cap and makes the nose cap go round and round by caudal gemel. Then the mantle break away from the forebody when the rotate angle arrive at the preconcerted angle, the aerodynamic force is several orders of magnitude greater than the inertial force, the nose cap trajectory is absolutely controlled by the aerodynamic force and the mantle statement changes violently. The two nose cap have a symmetrical motion distance and pitch angle in the angle of attack α=0°, however, the separate characteristic is unsymmetrical in the angle of attack α=-5°. The angle of attack for the supersonic vehicle has a prominent effect on the motion characteristic for the two nose cap. The study can provide an according and reference for the nose cap separation precept and flighting control system.