The spectral behavior of polychromatic spatially fully coherent light diffracted by an annular aperture in near field is studied in this paper basing on the research of it in the far field. Detailed numerical calculation results are presented and illustrated. It is shown that the spectrum in the near field is generally different from that at the aperture. It is proportional to the spectrum at the aperture and a spectral modifier which depends on the central obstruction ratio ε, the distance z between the aperture and the observe point and the distance r of the observe point to the z axes. With the increase of the central obstruction ratio ε, the spectrum of near field translates into far field gradually. Detailed numerical calculation results indicate that significant spectral changes take place in the vicinity of intensity zeros (These corresponding points are singularities), i.e., the spectrum is red-shifted at the side of the singularities, blue-shifted at the other side of the singularities and exhibits a rapid transition at the positions of the singularities between them.