Abstract: This paper proposes a single-beam differential relative navigation method to solve the relative navigation requirements of Distant Retrograde Orbit (DRO) satellite formation in cislunar space. The formation of two DRO satellites can be covered by a beam of measurement sent by a Low Earth Orbit (LEO) satellite, thus establishing two Satellite-to-Satellite Tracking (SST) links with the LEO satellite at the same time. Then differential measurement data can be obtained by these two SST links. This method can get relative states of the DRO satellite information by combining the differential measurement data and three-body orbital dynamics model. DRO is in the space with high asymmetry of the Earth-Moon three-body gravitational field, according to the LiAISON principle, a SST link established between the satellite running on this orbit and an LEO satellite can realize autonomous navigation, thus determining the absolute orbit states of one of the DRO formation satellites and the LEO satellite. The single-beam differential relative navigation method uses the absolute states of two satellites as constraints, and the advantage of using differential measurement data to eliminate common errors can obtain high-precision relative states of DRO satellite formation. In the simulation test, the relative navigation performance of the single-beam differential relative navigation method of the short-distance DRO satellite formation (inter-satellite distance of 50 km) and the long-distance DRO satellite formation (the distance between the satellites is about tens of thousands of kilometers) is tested. And the results show that, when the inter-satellite ranging noise is 0.5 m, the relative navigation accuracy calculated by the method proposed in this paper is 5 m (1 σ), which is 4 times higher than the relative navigation accuracy calculated by differencing the absolute orbit.