Nd:GGG grown with Czochralski method is a very promising laser crystal used in the strong lasers. The precursor of GSGG was prepared by coprecipitatiom method, and polycrystalline material of GSGG was obtained at the lower sintered temperature. Scandium-containing garnet Nd:GSGG of (?)26 mmx45 mm, which are free of scattering, air bubbles, cloud layer and crack, was grown by Czochralski method. The phase transition of co-precipitating precursors of GSGG sintered at the different temperatures was studied by X-ray diffraction, which indicated that the precursors were converted into the polycrystalline GSGG at 900℃. The phase transition temperature is 200℃ lower than that of solid state reaction method. Meanwhile, the structure of the polycrystalline GSGG and single crystal Nd:GSGG were studied by X-ray diffraction. Their lattice parameters were computed by the least square method with the extrapolation function f(θ) = sin θ-sin1-T θ(T = 20), which are 1.257547 nm and 1.256163 nm, respectively. It is possible that the lattice parameter difference results from the difference of the ingredient Ga in the polycrystalline GSGG and single crystal Nd:GSGG.