Abstract: Methods of single frequency carrier phase-based relative orbit determination(OD) and kinematic network OD for low-earth satellite are developed. From theresults calculated using L1 data collected by GPS/DR onboard Topex/Poseidon,we can draw following conclusions: (a) the accuracy of single frequency carrierphase-based relative OD may attain the order of a few decimeters; (b) the accuracyof relative OD depends on the data quality of ground tracking stations; (c) theaccuracy of kinematic network OD is equavalent to a weighting among relative ODsof different ground tracking stations and can improve the reliability and precisionof OD due to its redundant condition and good geometric configuration.