While　inertial　measurement　unit　(IMU)-based　motion　capture　(MoCap)　systems　have　been　gaining　popularity　for　human　movement　analysis,　they　still　suffer　from　long-term　positioning　errors　due　to　accumulated　drift　and　inefficient　data　transmission　via　Wi-Fi　or　Bluetooth.　To　address　this　problem,　this　study　introduces　an　integrated　ultrawideband　(UWB)-IMU　system,　named　UI-MoCap,　designed　for　simultaneous　3D　positioning　as　well　as　wireless　IMU　data　transmission　through　UWB　pulses.　The　UI-MoCap　comprises　mobile　UWB　tags　and　hardware-synchronized　UWB　base　stations.　Each　UWB　tag,　a　compact　circular　PCB　with　a　3.4cm　diameter,　houses　a　nine-axis　IMU　unit　and　a　UWB　transceiver　for　data　transmission.　The　base　stations　are　equipped　with　a　UWB　transceiver　and　an　Ethernet　controller,　ensuring　efficient　reception　and　management　of　messages　from　multiple　tags.　Experiments　were　conducted　to　evaluate　the　system＇s　validity　and　reliability　of　3D　positioning　and　IMU　data　transmission.　The　results　demonstrate　that　UI-MoCap　achieves　centimeter-level　3D　positioning　accuracy　and　maintains　consistent　positioning　performance　over　time.　Moreover,　UI-MoCap　exhibits　high　update　rates　and　a　minimal　packet　loss　rate　for　IMU　data　transmission,　significantly　outperforming　Wi-Fi-based　transmission　techniques.　Future　work　will　explore　the　fusion　of　UWB　and　IMU　technologies　to　further　enhance　positioning　performance,　with　a　focus　on　human　movement　analysis　and　rehabilitation　applications.