© 2015, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. In this study, the formation of bow-shock and its instabilities have been studied in front of axisymmetric blunt nose shapes, at hypersonic Mach number 7 to understand the physics of bow-shock instabilities. The three geometries have been investigated as concave hemispherical shell (with negative curvature), convex hemispherical shell (with positive curvature) and circular at plate (with zero curvature), with same characteristic diameter. The lift and drag force measurements and unsteady pressure measurements were performed for all three geometries. The bow-shock visualizations have been carried out by Schlieren system, using high-speed camera at 10000 fps in hypersonic wind tunnel. By using image processing method, bow-shock unsteadiness has been analyzed for all three geometries. The large deformations in bow-shock in front of hemispherical concave shell have been analyzed with unsteady pressure measurement and shock displacements at the center and the edges of the geometries. It is observed that the large bow-shock deformations for convex, at and concave shaped blunt nose sustain within time order of 0.1 ms, 0.5 ms and 100 ms to 200 ms, respectively.