A simulation model was developed to describe the anomalous transient enhanced diffusion of implanted boron in silicon characterized by profiles in which a secondary peak is formed near the amorphous/crystalline interface. In this model, the diffusion equation was obtained by assumining either a self-interstitial/boron atom exchange mechanism or an intrinsic point defect/boron atom pair formation and diffusion. The initial distribution of excess point defects was proposed based on a depth-dependent implantation damage distribution. The effective diffusivity of point defects and their initial distributions were adjusted during the simulation to obtained the best fit to the SIMS boron diffusion profiles.