Wireless sensor networks (WSN), which integrates the functions of data collection, data processing and wireless communication, reinforces human ability in information obtaining. There are abundant research topics which are considerably challenging in WSN. As fundamental issues, deployment and localization are basis for the applications of WSN. The deployment, to place sensor nodes with proper strategy to meet some particular requests, determines WSN performance of target detection. Localization in WSN includes node localization and target localization. The former is the premise of the latter, and affects the precision of target tracking. Deployment and localization of WSN applied in target tracking are studied as follows: 1) Considering great cooperative capability of sensor nodes, present a deployment strategy based on detection fusion. 2) Present multipath error analysis of Radio Interferometric Positioning System and propose a modified Particle Swarm Optimization based localization method for it. 3) Design two tracking algorithms based on a distributed particle filter and discuss performance metrics in terms of tracking performance, communication cost, energy cost, and tracking response time.