The utilization of pure waterjet for Incremental Sheet Metal Forming (ISMF) is growing. However, the fatigue of pure waterjet nozzle is not fully clear. In the current study, based on the computational fluid dynamics (CFD) and finite element analysis (FEA), the fatigue failure of pure waterjet nozzle was simulated and analyzed. The influence of uneven equivalent stress distribution and generation of cavitation on nozzle fatigue failure was discussed. The results obtained from two simulations (velocity, pressure) show a good agreement with the theoretical predictions, which indicates that the approach based on CFD and FEA is absolutely feasible. Due to the uneven equivalent stress distribution, there is the first failure point inside the nozzle, which reduces the whole life of the nozzle. The unreasonable nozzle structure is one of main causes of cavitation generation; cavitation damage is reduced by optimizing the structure to improve the overall life of the nozzle.