Modeling and performance evaluation plays an important role on the theoretical research and technology improvement of the Internet of Things (IoT). In the study, the modeling and performance evaluation method based on Petri Nets and behavior expression is presented. Firstly, according to the system information flow chart, the constraint relationship between places and transitions are identified and then graphic Extended Stochastic Petri Nets model is built up; next, the behavior expression method is adopted to obtain a variety of performance indicators. A case is also presented to verify the effectivity and efficiency.