The dynamic equations of system centroid orbit and tether oscillation were established. And the dynamic characteristics of tether oscillation without tether control and the effects of tether control on tether oscillation were analyzed. An expect rate of tether which suppress tether oscillation was constructed and tether tension control law was designed. Simulation results indicate that when there is no tether control, tether oscillation is in periodic reciprocating motion around the equilibrium position. The tether tension control is continuous and smooth, which makes tether actual length keep well track of the expected length, and the tether oscillation is suppressed effectively at the same time.