Abstract: J_2 perturbation has a great effect on the relativemotion of low-earth orbiting satellites in formation flying and has effecton lives of satellites directly. J_2 perturbation makes the relativeorbit drift in the in-track direction, nutation or procession. Firstly, thispaper investigates the magnitudes of the first order approximations andinfluencing factors for drift rate, nutation rate and procession rate.Secondly, a rule is given to estimate the relationship of drift and rotationfor a relative orbit. Finally, using the rule, effects of the differences inorbital elements of leading satellite and following satellite on the driftand rotation of the relative orbit are investigated. The conclusions in thepaper could be as the reference to determine initial orbital elements ofsatellites formation design when considering J_2 perturbation.