Wireless sensor network (WSN) has been widely adpoted and deployed for various applications. Due to the need for wider-area monitoring with cost-down manners, the notion of mobile WSN has been proposed recently. In this article we proposed the architecture of mobile WSN and investigated it potential applications. First we discussed the necessary components to construct a mobile WSN. The types of connectivity in mobile WSN is also discussed, which can be categorized as intermittent and reliable connected networks. Furthermore, two real-world cases are illustrated in this article to demonstrate the feasibility of deployment of mobile WSN.