This paper talked about spacecraft formation flying control. Leader-flower structure is used in formation flying. A non-linear PID controller is designed based on predictive control. The formation relative equation is obtained from nonlinear Hill equation. First, the frequency control is achieved with the using of predictive control algorithm. In control frequency, disturbances have been replaced from disturbance observer. Equations are rewritten in the form of PID gains. Stability of the closed-loop system is proven by closed-loop error dynamics. Nonlinear PID controller performance in the pursuit of desired arrangement has been tested in simulations. Also effects of various factors on the quality of controller results are studied. It is shown that choosing predictive horizon time and disturbance observer gains have the most effect on system response. It is shown that if predictive time increase the settling time increase and the control effort decrease. if disturbance observer gain increase from a limit, it has no effect on settling time but control effort increase. As shown in simulation, the tracking response show the controller method ability. the simulation show the ability of this nonlinear control method in tracking.