Abstract: The strictly regressive orbit is designed under high precise orbit dynamic with high order non spherical gravitational field of earth. The strictly regressive orbit is one kind of sun synchronous repeat track orbits, of which the beginning and ending space trajectories over repeat period in WGS84 coordinates are highly coincided. The on borne tube navigation algorithm sets a strictly regressive orbit designed before launch as reference orbit, based on which a virtual formation is formed with the real satellite. Since the effect of air drag is not considered in the design process of strictly regressive orbit, the satellite in orbit can calculate the orbit decay situation and orbit decay rate caused by air drag. To reuse the reference orbit, the effects of third body perturbation of sun and moon are also not considered in the design process of strictly regressive orbit. Therefore the long period motion characteristics of orbit inclination are determined during in orbit flying. Based on the telemetering data of LT1 satellite, the orbital characteristics mentioned above are analyzed in this paper.