The micro-lens array is the core component of Shack-Hartmann wavefront sensor. According to the phase modulation principle of liquid crystal spatial light modulator (LC-SLM), the LC-SLM generates dynamic micro-lens array with tunable focal length, aperture size, and arrangement of sub-apertures. Hartmann wavefront sensor based LC-SLM is used to split the incident light. The average slope of each sub-aperture is tested. The phase distribution of wavefront is reconstructed. Then the wavefront aberration is corrected in one step. After aberration, the Strel ratio of the light wave changes from 0.12 to 0.59. For the micro-lens array generated by LC-SLM, heir focal length, adjacent spacing, numbers and performance are discussed in theory and experiment. The results show that the dynamic Hartmann sensor using LC-SLM has the advantages of tunable sub-aperture size, numbers and arrangement according to the external conditions.