When developing critical and complex systems, the analysis and the performance evaluation of the designed system is a challenging task. Wireless Sensor Networks (WSNs) are examples of such systems. A WSN consists of a large amount of distributed nodes which monitor physical or environmental conditions. In this paper, we address the problem of how WSNs must be designed to have good performances in particular the energy consumption and the packet loss ratio. To do so, we use an expressive kind of Petri Nets called Deterministic Stochastic Petri Nets. To show the applicability of the proposed model, one of routing techniques dedicated for WSNs is presented.