Abstract: Element mutual diffusions during hot iso-static pressing (HIP) diffusion bonding were simulated using DICRTRA-THERMO-CALC software. The calculating results show that the simulation regulations are agreeable with experimental results. Based on this simulation model, the effect of hold time and temperature on Al mutual diffusion during HIP were calculated, showing that this dynamic computer simulation can offer the processing prediction and the optimum HIP diffusion bonding processing.