||Great benefits could be envisioned through the deployment of wireless sensor networks for a wide range of applications, coving the domain of commercial, military and home. In this project, we work out a Moving Object Counting system, which can detect and track the movement of pedestrians and counting the corresponding number. Such a system can be applied in pedestrian traffic management, tourist's flow estimation, optimized facility management, security surveillance, etc. Our design is based on a cost-effective ultrasound sensor network. We introduce the implementation details related to our system, including sensor clustering, time synchronization, node communication, and the system architecture and deployment. We will discuss the major difficulties and challenges that we have encountered, and propose feasible solutions to them. Extensive experiments have been made, which evaluate the performance and demonstrate the efficiency of our Moving Object Counting system.