In this paper, according to the principle of non-mechanical structure, the liquid crystal spatial light modulator is used as the modulation device, and a new way to realize the deflection control of the beam is proposed. The theoretical model of beam deflection control is established. The relationship between the radius of the first ring of the Fresnel lens and its corresponding focal length is analyzed. The range and accuracy of the beam deflection angle are analyzed under different center radii. The relationship between the deflection angle of the beam with the same displacement distance at different center radii is analyzed. The relationship between the beam deflection and the fresnel phase diagram size and displacement factor is obtained. Within a certain range, the smaller the radius of the first ring of loaded fresnel phase map, the greater the deflection angle. According to the experiment expected to reduce the phase map radius, with the follow-up optical path should be able to improve the scope of beam scanning.