Yb0.05:Gd0.20Y0.75Al3(BO3)4(Yb:GdYAB) and Yb0.05:Y0.95Al3(BO3)4(Yb:YAB) crystals have been grown using the flux method. Their absorption and fluorescence spectra were measured at room temperature and important spectroscopic parameters were calculated. Through the comparison of spectroscopic parameters for the Yb:GdYAB and Yb:YAB, it is indicated that the 5 at% Yb:GdYAB crystal is an excellent self-frequency-doubling laser crystal and potential candidate for compact, efficient thin chip lasers.