Abstract: The authors measures and discusses the applied characteristics of single grain giant magnetostrictive material Tb_0.27Dy_0.73Fe₂. On this basis, magnetostrictive micro- actuator is developed. When field intensity is 9.55×10⁴ A/ m, the displacement output of the actuator is 20μ m, the discrimination is 0.1μm, the linearity is almost 4% and the output of static force is 1 109 N. The range of working voltage is 1 - 15 V, the working current is below 3 A. The dimension of actuator is φ = 40 mm, L = 60 mm. It has small volume, generates little heat and works stably.