Hydromechanical deep drawing is a new process in sheet metal forming. In hydromechanical deep drawing, a chamber of fluid replaces the matrix and the final form of part is determined based on the form of rigid punch. This process can produce parts with more drawing ratios than traditional deep drawing. In this paper, the hydromechanical deep drawing (HDD) of square parts was studied using the finite element method (FEM), and the effects of different parameters of the process such as pre-bulging pressure, chamber pressure, and friction coefficient on the thinning were investigated. Simulation is done using Abaqus software. St12 sheets have been formed and the effect of parameters on thickness distribution is determined. A study was also carried out using an experimental setup to verify the FEM results. Results show that flange wrinkling decreases by increasing chamber pressure. Also selecting appropriate pre-bulging pressure can decrease the thinning significantly. Finally, the numerical results were compared with experimental data. Manuscript profile