Tb3ScxAl5-xO12(TSAG) crystal is a magneto optical crystal material with excellent performance. Solving the cracking problem during the growth of large-sized TSAG crystal is of great significance for its application in high-power magneto-optical isolators. The segregation law of Dy and Lu during the crystal growth process with Czochralski method was investigated, and the effect of Dy and Lu doping on the crystal properties TSAG were also clarified. The results indicate that Dy and Lu doping are helpful to solve the cracking problem of large-sized TSAG crystal. The obtained TSAG crystals have good internal quality, and the resulting extinction ratios are all greater than 33 dB. Lu doping improves the Verde constant of TSAG crystals, while Dy doping has no significant effect on the Verde constant of TSAG crystals. The magneto-optical properties of Dy and Lu co-doped TSAG crystals are basically similar to those of TSAG, and the prepared crystals meet the requirements for high-power laser isolators.