Abstract: In Chinese ink wash drawing‚a self-similar silhouette is generated on Xuan paper while ink diffuses.An approach based on fractal is presented to simulate the diffusion border.This approach first generates a diffusion stroke through fluid simulation model.Then it simulates an irregular outer border on the diffusion stroke.Furthermore‚it fills the interspace between them to make the diffusion effect more natural and true to life.Experimental results demonstrate that the diffusion effect simulated by fractal is similar to the real effect of ink wash drawing.