Abstract: Abstract：Based on intersatellite measurement and reduced relative orbit elements of satellites, an improved approach of formation navigation is investigated. The traditional navigation algorithm transforms the relative orbit elements into the relative position by measuring equations, which results in nonlinearity of the navigation model. In the improved approach, the difference of semiaxis is estimated via the excursion in alongtrack. The problem of linearization error can be solved by using the difference of semiaxis, which has an important influence on relative dynamic of satellites. The method can realize a longterm stable and highprecision navigation of satellites formation.

Key words: Keywords：satellites formation, longterm stabilization；relative navigation, reduced relative orbit elements, difference of semiaxis