Abstract: The approaching strategies for on-orbit servicing are investigated to solve how to approach the target vehicle for the servicer spacecraft.According to Hill′s equations,four fundamental relative motions were presented by analyzing the relative motion between two orbiting vehicles.And then,by combining the fundamental relative motions,four possible approaching strategies named Approaching from Different Plane,Approaching by Hovering,Approaching from All Directions and Approaching along the Same Orbit,were introduced and analyzed.The results show that the strategy of Approaching from Different Plane could save an amount of fuel while other strategies have wide range of application.