In practical applications, it is always necessary to convert the intensity distributions of the laser beams into desired profiles for improving the efficiency. Based on the high spatial resolution and programmable controller of the phase-only liquid crystal spatial light modulator, an adaptive near-field beam shaping system composed of simulated annealing algorithm is built. The feasibility of the system is validated by translating an ideal Gaussian beam into a flattop beam in the near field theoretically. Finally, the experimental closed control loop system is built to convert a quasi-Gaussian beam emitting from a solid laser into a quasi-flattop beam in the near field. The experimental results show that 64% energy of the actual output beam concentrates in a region which has a relative root mean square (RMS) intensity variation less than 9%.