Abstract: The effect of heat treatment on the magnetostrictive properties of a (110)-oriented polycrystal Fe₈₃Ga₁₇ alloy was investigated. It was found that the saturation magnetostrictive strain of the quenched Fe₈₃Ga₁₇ alloy exceeded 300×10^-6 under a compressive stress of 25 MPa. The results of Neutron diffraction and differential thermal analysis confirmed that slow cooling leads to the change of phase structure which resuits in the change of magnetostrictive strain. The increase in magnetostrictive strain of the Fe₈₃Ga₁₇ alloy treated by quenching is explained as that the long-range DO₃ is suppressed.