Firstly, the definition, origin, development and application status of UWB technology is introduced. The PLUS target tracking and locating platform based on UWB technologyis established and debugged. This platform is the basis of the subsequent theoretical research and practical application.Secondly, the theoretical basis of UWB locating system is introduced. Through comparing many dferent locating methods, the Time Difference of Arrival (TDOA) algorithm is selected as the basic theoretical algoritm of the proposed locating system.The NLOS mitigation algorithm which aims to increase the locating accuracy is introduced and investigated as well.Thirdly, the software design and implementation of PLUS locating system is investigated. In order to track and locate the moving target, the Microsoft Visual Studio 10 version is sected as the development environment and C# as the language for the subsystem of locating software.The specific function of the developed system is listed as follows:1. System configuration and data source selection. Identify the reader, the MAC address of every reader, measured data and correction data, such as the position coordinates of the reader. Set a known value to the Z coordinates of every reader,and read the tag position information in real time from log file, simulation data or IP address.2. Network communication. Read the data with TCP/IP protocol in real time and synchronise the resource with multithreading coding method to avoid the threadlocking when the tracking is ceased.3. Data processing. Obtain the TOA information data and have them displayed, and then get the real-time position information after the processing. A Graph User Interface (GUD) is designed to display the tracking location in real time.The master control interface of PLUS locating system is developed with Windows form designer, including menu bar, toolbar, status bar, tracking area, tag bar and alarm bar.Graph the tracking ffects with GDI+ in form designer, and obtain the tag information with ADONET and Access 2003 database. The master control interface is able to locatethe tag and display the tracking efets in real time. In conclusion, the disadvantages of the developed system and future work are analysed.