The liquid crystal spatial light modulator is an effective method to change the quality of the laser beam light field distribution, and the phase hologram is the key to the function of the pure phase liquid crystal spatial light modulator. An improved iterative algorithm for beam shaping is proposed, which is improved on the basis of the traditional G-S algorithm. The improved algorithm is more universal, has better rapid convergence and design flexibility. By proposing an optimization factor ζ, the original uneven light intensity distribution in the light field is compensated, and the advantages of the G-S algorithm that the light field is reshaped by the clear boundary are retained and the uniformity of the light field distribution is improved. The experimental results show that the liquid crystal spatial light modulator can improve the nearfield beam quality very well, the energy utilization rate of the shaped output beam is 97%, and its top unevenness is 25.6%. © 2021 SPIE.