Abstract: Aiming at the situation that four or more receivers of ultra-wideband (UWB) positioning technology are needed to directly receive signals from transmitting terminal.Positioning method for only three receivers with TDOA was proposed using high time resolution of UWB signals and character of big flat reflective surfaces in the environment to estimate the 3D position.This method can position applying of the information of multipath delay and reflector position.The experiment results showed that this method could determine the transmitter's position with better accuracy than the conventional assumed height TDOA method.