In this article, a new design methodology of systolic arrays based on Petri nets is presented. As regards to traditionnal methods, it takes advantages of using a model very useful in numerous industrial and research applications. After a short reminding on specific properties of basic systolic architectures, the different steps of the method are presented. Architectural PetriNets enable not only the modelling of a systolic architecture, but also the environment interfaces. An example is described, relative to the matrice multiplication which is used in an application of stereoscopic image processing for 3D reconstruction environment.