How to get a high-quality pseudo-thermal light source is very important to the intensity quantum imaging experiment. The reason of using pseudo-thermal light instead of true thermal light is the coherence time of true thermal light is too short to respond by the common detectors, and its intensity very low. It is a common method to use dynamic speckles produced by the laser transmitting through a rotary ground glass as a pseudo-thermal light source in order to overcome these problems. The paper proposed using a liquid crystal spatial light modulation (LC-SLM) controlling the laser beam to get a pseudo-thermal light source. It can simulate the intensity fluctuation of true thermal light extremely, and it obeys to Gauss statistical distribution property. In addition, it is a non-mechanical system. The temporal and the spatial coherence can be treated separately, so the result is repeatable. The characteristic of the dynamic speckle is also studied.