Multi-focus images are acquired to apply in the shape from focus and multi-focus image fusion. In order to ensure that a series of multi-focus images contain the process of objects from blur to clarity and then to blur, researchers often need to spend a lot of time and effort adjusting the parameters of the equipment. To avoid frequent operations for equipment, this paper utilizes simulation to generate the multi-focus image of the virtual scene. Since the Gaussian blur of the image is close to the actual blur effect, we use the two-dimensional Gaussian function as the point spread function model of the optical imaging system and adopt the dynamic blur kernel to defocus the focused image through the computer. The researchers can obtain the corresponding multi-focus image by the set parameters. The experiment shows that the simulation results are consistent with the multi-focus image collected by the actual equipment when the parameters are the same. Therefore, the simulation parameters can be directly applied to the equipment.