Abstract: In the field of low Earth orbit (LEO) satellite navigation augmentation and radio occultation, users require high-precision and low-latency LEO satellite orbit information. The conventional approach is that low-orbit satellites transmit observation data and augmentation information to ground processing centers for the generation of precise satellite orbits. The latency in this approach depends on the satellite-to-ground link and augmentation information delay. To provide high-precision and low-latency orbit information, the feasibility of LEO satellite autonomous precise orbit determination based on Precise Point Positioning (PPP) messages is validated, and LEO satellite autonomous precise orbit determination based on PPP messages is proposed, using the Sentinel-3A satellite as the research subject. The results indicate that the three-dimensional accuracy of real-time orbit determination using single-system and multi-system autonomous PPP messages is 5.32 cm and 2.23 cm, respectively. The technique of multi-system autonomous real-time orbit determination based on PPP messages eliminates the waiting time for external information and achieves centimeter-level orbit accuracy, providing a feasible solution for future autonomous information processing in LEO navigation systems.