Transmitting optical information through scattering medium has broad application prospects in biomedical, aerospace and other fields. However, the light passing through the scattering medium will cause wavefront distortion and optical information blurring. Wavefront shaping technology uses a mathematical matrix to characterize the characteristics of scattering media, which can achieve refocusing and imaging after light propagation through the scattering medium. It mainly includes optical phase conjugation, optical transmission matrix and wavefront shaping based on iterative optimization. However, the iterative wavefront shaping is considered to be a cost-effective method. Based on the wavefront amplitude modulation technology, the wavefront amplitude of the incident light is continuously adjusted by using the optimization algorithm to find the corresponding wavefront amplitude distribution that can maximize the light intensity in the target area. The system generates binary patterns implemented with digital-micromirror device (DMD) based on on-off state of micromirror, where on stands for 1 and off stands for 0. DMD has a high refresh rate, enabling high speed wavefront amplitude modulation using the iteration algorithm. In the experiment, the scattering media is prepared with TiO₂, water and gelatin, whose persistence time are controlled with the water-gelatin ratio (WGR). In addition, the Pearson correlation coefficient (Cor) curve obtained by measuring 300 s under different WGR conditions, which shows that the greater WGR, the shorter persistence time. The experiment mainly studies the focusing of the spatial light through scattering media by wavefront amplitude modulation, and discusses the control ability of point guard algorithm (PGA) and genetic algorithm (GA) to the scattered light field with different persistence time in 64×64 segments. The experimental results show that the PGA can achieve higher enhancement factor and more uniform multi-point focusing than these of GA after 1000 iterations in the scattering medium with the same persistence time. The relative standard deviation (RSD) value is inversely proportional to the WGR value when multi-point focusing can be completed. We also demonstrate that GA can only achieve single-point focusing when WGR=40, and it can't accomplish multi-point focusing in self-made scattering medium. This study not only verifies a method to achieve focusing scattering light field, but also provides a new scheme for testing the performance of the iterative wavefront shaping.