The visual beauty bokeh effect cannot be taken by non single-lens reflex camera, therefore a simulation algorithm for depth of field is presented based on multi-focus image depth information extraction. The mathematical model of heat diffusion equation is built for the multi-focus images. The adaptive depth values of initial image are proposed to optimize the solution of partial differential equation. The foreground and background are acquired by splitting the adjusted depth image obtained through regularization. Also, a simulation algorithm for depth of field based on phased Gaussian kernel is proposed to simulate the blur effect in the background caused by a wide aperture camera. Compared with other published algorithms, the results show that this algorithm can not only extract the depth information of the image accurately but also simulate the real depth of field effect.