A novel sample rate adaptation technique is proposed for the wireless sensor/actuator networks with packet reordering. Considering network-induced delay and packet loss, a new technique for adapting the sampling interval to network parameters is studied in terms of the Reorder Density, such that a closed-loop switched delay system is presented by constructing state feedback controller. Furthermore, a criterion for stochastic stability of WSANs is derived based on the stochastic theory due to the subsystems subject to Markov chain. An adaptive controller is designed by solving linear matrix inequalities (LMI). An example is given to show the effectiveness of the proposed method.