Based on the scattering potential theory and the first-order Born approximation condition of weak scattering, the influences of the center position offsets and the boundary condition variations of the sub-wavelength spherical particles on the spectral density distribution of the scattered evanescent waves are studied. The near-field components of the scattering light are expanded in the angular spectra, and the double integral expression of the complex amplitude of evanescent waves is obtained. The angular and radial parameters are integrated with the numerical integral method, and the related distribution characteristics between the spectral density of evanescent waves and the scattering parameters are obtained. The results show that the scattered evanescent waves contain the characteristic informations of the center positions and the boundary conditions of the scattered particles whose radii are within the range of the effective scattering radius. These informations disappear rapidly with the increase of propagation distance. The study results are conducive for the detection and structural inversion of tiny particles with complex spatial structures.