In this thesis work, numerical simulation model of waterjet peening processing without abrasive particles has been developed to predict the effect of peening process. Two kinds of simulation are used through: one is quasi-static model and the other is transient dynamic model. The results are described by the residual stress after peening. ABAQUS software in applied in non-linear elastic-plastic FE simulation. Both quasi-static model and dynamic model are used to describe the initial interfacial pressure distribution in different theories. The models are qualified with Mises yield condition. Residual stress is calculated numerically and compared, somehow the result from static model is more stable and more research need to do on the dynamic model in the future.