© 2022 COSPARThis study is devoted Global Navigation Satellite System (GNSS) based fault-tolerant state estimation technique within formation satellite flight which used the pseudo-ranging distance model. Fault-tolerant Kalman filters obtain the relative satellite state estimations via measurement of the actual distance between 4 Global Positioning Systems (GPS) satellites and target/tracker satellites. The Keplerian equations and orbit elements are used for detecting target and tracker satellites’ dynamic models. J2 orbit perturbation is considered within the relative state estimation stage via covariance matrices of target and tracker satellites’ positioning stages. The novel approach is fault-tolerant relative satellite state estimations are proposed via two different techniques. One of them is reconfiguration fault-tolerant cluster satellite localization, and the other is adaptively faulting-tolerant cluster satellite localization. The Extended Kalman Filter (EKF) is used for target and tracker satellite orbital state estimations and measurement errors. The Reconfigurable and the adaptive algorithms detected and corrected the GPS measurement errors during relative satellite motion.