A piecewise linear JE recursive convolution finite-difference time-domain (PLJERC-FDTD) algorithm is applied to the study of the scattering characteristics of the hypersonic flow field with near wake region of conductive metal sphere. The effects of incidence wave frequency, incidence angle, scattering angle, polarization angle, altitude and Mach number on the radar cross section (RCS) are analyzed. The results illustrate that the forward RCS is the maximal RCS of all scattering orientations' RCS. The forward RCS increases with the rise of incidence wave frequency and Mach number, decreases with the decline of altitude when the Mach number is not less than 14 in this article. The backward RCS and the bistatic RCS of flow fields vary very small with Mach number, altitude and incidence angle for UHF, L and S band, the margin of the backward RCS between flow fields and sphere are small when the Mach number is not more than 10. The backward RCS of flow fields is more than the sphere's because of the formation of wide over-dense plasma wake, the curve of backward RCS varies when the incidence wave frequency can be approached by one line for L, S band if the incidence orientation is perpendicular to the X-axis and the Mach number is not less than 14.