The absorption spectrum of Nd3+ions doped into Gd3 Ga5 O12 (GGG) single crystal was analyzed in the visible and near infrared region. Its crystal-field and spin-orbit parameters were calculated with the DV-Xα method, which belongs to an abinitio calculation. Meanwhile, its free-ions and crystal-field parameters were also been fitted to the experimental energy levels in 300 K and 77 K with the root mean square deviation of 15.79 cm-1 and 11.48 cm-1, respectively. According to the crystal-field calculations, 156 levels of Nd3+ions in 77 K and 88 levels of Nd3+ions in 300 K were assigned. The results indicated that the fitted and calculated crystal-field parameters by DV-Xα are consistent very well. Finally, the fitting results of free-ions and crystal-field parameters are compared with those already reported for Nd3+:YAG.