Voice coil actuator(VCA) has the merits of no hysteresis, fast response and large stroke. It has been used in the secondary mirror of large optical telescopes. To improve its efficiency, a high efficiency moving magnetic voice coil actuator was designed. And a three-dimensional model of VCA has been built and analyzed with finite element analysis software to simulate its magnet magnetizing direction, magnet size, coil size and structure contributed to a more accurate result of the electromagnetic force and efficiency. In order to generate large electromagnetic force and high efficiency, the above parameters are simulated and optimized respectively. The result shows that the output force of the small caliber moving magnetic VCA is up to 0.43 N and the actuator constant is up to 0.9. There is a good linear relationship between the output force and the input current, which provides a theoretical basis for the development of the VCA for next generation deformable mirror.