Abstract: The stabilization of reentry vehicles is the one of the most important problems in the design of aerodynamics, it is vital to the safety of flight especilly in the re-entry process. The destabilization of reentry vehicles with blunt body and slender body was studied using the bifurcation theory of nonlinear autonomous dynamic system, and the analysis was validated by numerical simulation coupling Navier-Stokes equations and pitching motion equations. The investigations show that, in the process of the astronautic vehicles reentering into the atmosphere, if there is only one trim angle of attack, the characteristic of dynamic destabilization nearby the trim angle would be the hopf bifurcation with the Mach number decreased, and the form of bifurcation is subcritical or supercritical. While the trim angles of attack increased(commomly from 1 to 3) with the Mach number decreased, the behavior of dynamic destabilization nearby the trim angle is more complex. Three critical Mach numbers may be emergent in turn in the decreased process of Mach number, and at these three critical Mach numbers, the corresponding behavior of destabilization is saddle-node bifurcation, hopf bifurcation and homoclinic bifurcation.