XFill RTK technology is a new GPS-positioning method which was developed in the last two years. It extends RTK positioning for several minutes when the RTK correction stream from the base station is not available. In the area with a lot of horizontal obstructions and the radio signal from the base station is not continuous, this technology will improve the efficiency of the fieldwork. This paper introduces the principle of this technology and discusses a more advanced positioning method which can position indoor by satellite positioning system.