TbDyFe thin films were grown on silicon substrates by DC magnetron sputtering. The influence of sputtering power on magnetostrictive performance of TbDyFe films was studied by the composition and the microstructure of films. The results show that the composition of films varies with the sputtering powers, which results in the different magnetostrictive performances for different films. At lower sputtering powers, the films exhibit the microstructure of micro-cylinders with magnetic anisotropy from the nearly vertical direction to the substrate surface direction, as a result, the magnetostriction of films is significantly reduced. When sputtering power is up to 120 W, the films become homogeneous without any micro-cylinder, exhibiting good magnetostrictive performances.