Magnetostrictive and structural properties of sputter-prepared Fe71Co10Ga19 films on Si(100) substrates have been studied. The experimental results show that the saturation magnetostriction (λs) of the films is mainly dominated by the amount of m-D03 phase existed in the films through the modification of the sputtering parameters, including Ar gas pressure (PAr) and sputtering power (P). Large λs of 113.7 ppm is attained for the 200-nm-thick Fe71Co10Ga19 film made under the conditions of PAr = 30 mTorr and P = 40 W. Besides, the thickness (t) dependence of λs in the Fe71Co10Ga19 films is that: (a) in the region of 200 nm ≥ t ≥ 50 nm, λs increases from 113.7 to 164.7 ppm as t decreases; (b) in the region of 50 nm ≥ t ≥ 30 nm, λs decreases to 128.1 ppm as t continues to decrease. The increase of λs in the region (a) may be related to surface contribution involved by surface roughness. The decrease of λs in the region (b) results from the surface oxidation of film. The optimized λs of 113.7–164.7 ppm achieved for Fe71Co10Ga19 film in this study is superior to those (49–80 ppm) of the previously reported Fe81Ga19 thin films. The results of this work provide useful film-making information to obtain the Fe71Co10Ga19 film with outstanding structure and magnetostrictive properties for applications.