The hydroforming process to manufacture Al 5083 T-shapes with desired protrusion height and uniform thinning rate was evaluated by means of numerical simulation in this work. The optimization of process parameters and the prediction of forming effect were then carried out. Subsequently, the practical forming was performed based on the simulation results. It was obvious that the simulation results agreed well with the experimental ones. In addition, the streamline on the surface which formed in the hydroforming process was observed in the experiment.