The mathematic model of three-dimensional aluminum profile extrusion processes using finite volume method (FVM) was established in this paper. Basic theory and key technologies of this model were researched and built. Non-orthogonal blocked structured girds were used to fit complex geometries. Volume of Fluid (VOF) scheme was used to capture the free surface of the deforming materials. A program AE-FVM was written according to the above theories and equations. A thin walled aluminum profile extrusion process was simulated and optimized using AE-FVM. The simulation results were also compared with that simulated by Deform-3D and SuperForge in the same conditions. The feasibility of the mathematic model built in this paper was demonstrated by the simulation results comparison.