We used Raman spectroscopy to study the conformational changes of DNA induced by Cd2+ ions in different Cd2+ concentrations solution. The experimental results show that when the Cd^(2+)/PO^(-)_(2) ratio R increased from 0 to 3.0, the band 835.0 cm^(-1) shifted about 8 cm^(-1), and the overlapping spectra of 1446.0 and 1461.0 cm^(-1) separated and moved to 1441.0 and 1458.0 cm^(-1), respectively. This indicates that the conformation of DNA has changed from a "normal" B-form to a "modified" B'-form. At the same time, changes of other bands demonstrate that parts of base stacking collapse and some hydrogen bonds between AT are disrupted, AT base pairs are damaged more larger than GC base pairs.