Abstract: Based on the N-S equation, the third-order Weighed Essentially Non-Oscillatory(WENO) scheme is used to simulate the hypersonic flow around a blunt cone at zero angle of attack, and the basic properties of the entropy layer are studied. The method is proposed to determine the outer edge of boundary layer and entropy layer, and its applicability and limitation are analyzed. The numerical results show that there exists a "double generalized inflection point" phenomenon in the basic flow profile. The comparison between the results of the N-S equation and the Euler equation shows that the generalized inflection point in the entropy layer region is caused by the rotational flow in the entropy layer region, while the general inflection point in the boundary layer is caused by the viscous effect. This behaviour is the basis for the flow stability analysis. The influence of nose radius and Mach number is also analyzed on entropy layer characteristics. The results show that with the increase of Mach number, the flow in the entropy layer is increasingly rotational, and entropy layer has an enhanced influence on the downstream flow. The Reynolds number has slight influence on the entropy layer characteristics, and the size of the entropy layer is almost proportional to the nose radius.