Several experiments have shown that adding a fractional amount of Al can increase the elongation of the alloys and without the significant reduction of the magnetostrictive strain for Fe-Ga alloys. Furthermore, since the price of Al is lower than that of Ga, using Al to replace part of Ga in the (Fe₇₃Ga₂₇)_99.8Tb_0.2 alloy saves production costs as well. The (Fe₇₃Ga_27-xAl_x)_99.8Tb_0.2(x=0,1,2,3,4,5) alloys were prepared by vacuum arc furnace to study effect of Al addition on the microstructure, magnetic properties and mechanical properties of. The results show that the phase structure of the alloys is still A2 phase and Tb₂Fe₁₇ phase, and the metallographic structure is composed of cellular crystal and columnar dendrite. The decrease of lattice constant, the increase of (100) orientation and the generating of Tb₂Fe₁₇ at the grain boundary saliently exert effect on the magnetostrictive properties. The fracture morphology of the alloys is intergranular brittle fracture and cleavage fracture, the causes of fracture including segregation of Tb and Al elements. The parallel magnetostrictive strain (λ_∥) of (Fe₇₃Ga₂₄Al₃)_99.8Tb_0.2 alloy reaches 104 ppm. It is worth noting that compared with (Fe₇₃Ga₂₇)_99.8Tb_0.2 alloy, the λ_∥and elongation of (Fe₇₃Ga₂₅Al₁)_99.8Tb_0.2 alloy increase by 18.3% and 53.4% particularly, which also possesses the characteristics of high saturation magnetization (Ms), low remanent magnetization (Mr) and coercivity (Hc), thus cutting the cost in actual production while the tensile strength and Vickers hardness exhibit a slight descending trend. Therefore, it is important to study the micro-mechanism of Al addition on Fe-Ga alloys for the development of Fe-Ga alloys devices.