This paper is devoted that relative navigation of satellites which fly within a formation. The concept and the methods of swarm satellites technology and architecture are explained. The difference between the constellation and the formation architecture of satellites are focused. Analyses of relative motion between satellites are simulated by mathematical model which used Hill-Clohessy-Wiltshire (HCW) equations and Keplerian orbital equations. The results of the analysis show that all axes shift by formation. The control algorithms requirements of follower satellite are decided according to the drift of the all axes. Extended Kalman filters are used for optimisation, estimation and control stability of nonlinear orbital relative motion of satellites. At last, comparison of relative navigation models are focused.