The paper approaches the optimal design of the mechanical systems based on parametric technique in MBS (Multi-Body Systems) environment. The optimization process is developed in five steps: parameterizing the virtual model for creating the relations between the objects (points, markers, bodies, constraints, forces), defining the design variables, defining the design objective and constraints, performing parametric studies in order to identify the sensitivity of the design objective at the modification of the design variables, and optimizing the model on the basis of the main design variables (with great influence on the design objective). For applying the optimization procedure, a solar tracking system used for increasing the energetic efficiency of the photovoltaic modules has been considered. The study is performed by using the MBS environment ADAMS of MSC Software.