Abstract: To investigate the dynamic stability of the non-spinning blunt cone, wind-tunnel free-flight tests with biplanar optical system, were conducted at Mach 6 in the hypersonic wind tunnel. The tests show that coning motion appears for all the models,and in the range of viewing area the amplitude of angle of sideslip is larger than that of angle of attack, though only angle of attack is preset. For all the models, the amplitude of both angles of attack and sideslip is no more than 10 degree, while damping moment shows obvious nonlinearity and static moment exhibits approximate linearity. One of the models shows the tendency of limit planar motion or limit coning motion with small amplitude of angle of attack, others all tend to limit coning motion. End cover has little effect on the angular motion of the models, while the protuberance symmetrically placed on the model tail can affect the transformation of amplitude of angular motion, and the fluctuation of angular motion amplitude is obviously smaller for models with strake.