A novel nonlinear optical crystal Ca3Ta(Ga0.7Al0.3)3Si2O14 (CTGAS) was successfully grown by the Czochralski method. The structural, spectroscopic and thermal properties have been systematically investigated, and the laser frequency doubling process has also been explored. Excellent thermal properties have been presented, such as moderate thermal conductivity, high specific heat, and low thermal expansion anisotropy. The electronic structure and optical properties have been investigated using the XPS technique and simultaneous assisted first-principles calculations. The optimal phase matching in type I (40.45°, 30.0°) and type II (64.73°, 0°) orientations were determined, frequency-doubling output was achieved in type I and type II, with laser energies of up to 10.04 mJ and 10.14 mJ obtained @ 532 nm, and optical-to-optical conversion efficiencies of 14.04 % and 17.21 %, respectively. The experimental findings demonstrate the great potential of CTGAS crystal as a frequency-doubling material.