Abstract In this paper, we analyze the feature of ultra-wide band (UWB) pseudo range, which is generated by method of time of flight (TOF). By applying Kalman filter and its transformation to the original TOF measures, we detect and remove measures with error as well as lower the noise of TOF measures. We build a model to correct system error of TOF measures by comparing it with known distance. The positioning result shows that as system error gets well corrected, the precision of UWB positioning reaches a level of 10 cm in static mode, and a level of 0.2 m in kinematic mode, while the path of object keeps smooth.