In order to meet the needs of calligraphy and digital creation of ink wash painting, this paper establishes a dual-layer paper simulation model to achieve the effect of irregular diffusion of ink on rice paper during the ink creation process. The duallayer model divides rice paper into a contact layer and a diffusion layer. By extracting the range of the user's input strokes and using the relevant information as the basis for initializing ink in the contact layer, the ink stored in the contact layer will proportionally flow to the diffusion layer. The diffusion process of ink in the diffusion layer is simulated using an improved coefficient diffusion equation. Experimental results demonstrate that the model can realistically simulate the ink diffusion effect in the ink creation process in a real environment, providing convenience for artists in digital platform creation.