Abstract: The threedimensional intensity distribution of the partially coherent beams focused by a lens is investigated. It is shown that the focused intensity distribution near the geometrical focus is dependent not only on the intensity distribution of the incident partially coherent beam, but also on the degree of coherence. Based on this point, a novel method is presented for achieving a quasi-ellipsoid light cage profile near the geometrical focus by modulating the spectral degree of coherence of the incident partially coherent beam. The modulation can obtain the desired three-dimensional intensity distribution and control the aperture of the ellipsoid light cage by choosing the appropriate parameters of spectral degree at the lens plane without changing the incident beam. The method is of th