The high average power solid state laser (HAP SSL) crystal Nd3+∶Gd3Ga5O12 (Nd3+∶GGG) has been grown by the Czochralski method. (444) double-crystal rocking curve for Nd3+∶GGG indicates that the crystal has a good quality. The absorption and emission spectra of Nd3+∶GGG crystal at room temperature have been studied. The relationship between the energy level scheme and the emission spectra has been analyzed. The absorption, emission cross-section and fluorescence lifetime have been estimated as 4.32×10-20 cm2, 2.3×10-19 cm2, 240 μs, respectively. The spectroscopic parameters of Nd3+∶GGG and Nd3+∶YAG crystal have been compared, and the Nd3+∶GGG crystal has many advantages over Nd3+∶YAG.