The numerical simulations of selected thixoforming processes using an own mathematical model describing metal alloys in the semi-solid state are presented. The model has been implemented in the original computer software used finite element method in 3D geometry. These simulations concerned characteristic processes of thixoforming like: compression experiment for the cylindrical billet of the aluminium alloy, moulding of the material with the free surface, thixocasting of a car's steering axle.