Most of bacterial species do not exist as a solitary cells but organize them into colonies known as biofilms. These colonies usually have complex structures with folds and wrinkles which contain a lot of information about bacteria, therefore simulation of biofilm development can be quite beneficial in industrial and medical applications. Since biofilm growth is a very complex process numerical methods are required to simulate it. We use a model based on Foppl-von Karman equations which we solve by finite element method. To apply this method we rewrite the equations in a weak form where the target functional is divided into two parts: deformation of the film as an infinitely thin surface and a regularization term related to bending energy. To increase computational speed and decrease required memory we use multigrid technique. Developed numerical procedure allows to simulate growth of biofilm using large number of elements and thereby catch even very small wrinkling patterns with high accuracy.