Abstract: The time delay effects of the boundary layer transition movement on the surface compared to aircraft pitching oscillation should produce serious unstable aerodynamic moments, which probably decrease the aerodynamic stabilities in the pitch direction, even leading to unpredicted pitching divergence in the reentry flight of the blunt cone. A boundary layer dynamic transition test technology of the blunt cone in the hypersonic wind tunnel is improved, using a gas bearing as support of the test model in order to realize free rotation of the test model in the longitudinal direction with extremely low damping moment. In addition, an infrared thermo-graphic system is used to observe and estimate the boundary layer transition distribution on the model, to study the dynamic coupling phenomenon and interaction between boundary layer transition and longitudinal rotation of the model. A series of tests are completed using the blunt cone model of which the half cone angle is 9 degree, to study dynamic coupling effects between boundary layer transition and longitudinal rotation. As a conclusion, an unsteady oscillation phenomenon of angle of attack was observed when dynamic boundary layer transition occurred, and at the same time, the delay phenomenon and delay time of boundary layer transition to angle of attack rotation were identified.