Various researches have been performed on the positioning system using satellites due to the increasing demand in the whole world. Those researches are aiming at construction of convenient system. Global Positioning System (GPS) are generally used as the worldwide satellite positioning system. Precise positioning with GPS requires revisions of information from a base station There are some limitations by using the base station. We study the relations between positioning result and each error factor in GPS, and propose a new positioning algorithm for precise positioning.