Giant magnetostrictive actuator characterized with strong bias magnetic field was designed to control the injector bullet valve opening and closing. Working principle of the actuator was described and suitable sinusoidal signals were analyzed by its bias characteristics. Semistatic model of the actuator displacement was established through reluctance theory, J-A model, quadratic domaintransfer model and linear system theory. Based on the model, the relationship between displacement and current amplitude under square signal was achieved, so did the displacementcurrent curve under sinusoidal signal and the displacementtime curve under square signal with the amplitude of 3A. Experimental system for the actuator was established, and the signal directions were recognized by testing under square signals with the same value while opposite directions. The testing displacements under sinusoidal and square signals were acquired. From the results, the displacement amplitudes under square signals and displacementcurrent curves under sinusoidal signals, calculated through the model, were similar to the testing results. Then the validation of the semistatic model was verified. The simulation of the actuator with an ordinary electrical injector input was done. With the square signal input in the amplitude of 3A, the steadystate displacement of the actuator was above 30μm, responding time was about 10μs, and overshoot was 0. The simulating results showed good performance of the actuator.