Based on the propagation theory of partially coherent light,the spectral shift and spectral switch of partially coherent modified Bessel-Gauss beams passing through an aperture lens are studied. Numerical results show that the spectral shift and spectral switch of partially coherent modified Bessel-Gauss beams are dependent upon the spectral degree of coherence,Fresnel number and truncation parameter. The number of spectral switch increases with increasing Fresnel number and truncation parameter,but decreases with increasing spectral degree of coherence. When the truncation parameter is larger than a certain value,the spectral switch disappears. For example,when the spectral degree of coherence equals to 0.5,and the truncation parameter is larger than 2.2,the spectral switch disappears and there is only the blue shift.