Tb3Ga5O12 crystal is a mainstream commercial material with good magneto-optical performance, but it suffers from serious gallium oxide volatilization during the growth process, which makes it difficult to meet developing requirements in high power applications. Tb3Al5O12 crystal, which shows a large Verdet constant, is difficult to grow due to its incongruent melting nature. Therefore, it is urgent to explore new high-quality magneto-optical crystals to meet the needs in high power applications. In this work, a series of Tb3AlxGa5-xO12 (TAGG) magneto-optical crystals with high aluminum content were grown by the micro-pulling-down method in a mixed atmosphere of high-purity nitrogen and carbon dioxide. The result of the rocking curve shows the as-grown TAGG magneto-optical crystal has high crystal quality. The transmittance spectrum and magneto-optical characteristics test results show that, the TAGG crystal shows a higher transparency and a larger Verdet constant compared with the traditional Tb3Ga5O12 crystal, which is a very promising low-cost magneto-optical material for high power laser systems.