Tether technology is highly significant for the realization of large space flexible structures. It is possible to decrease the weight of a structure by employing tether on the system. In addition, a tether system can be employed to increase the stiffness of space structure systems and also to suppress the vibration of flexible space structures. When tether is used in a mission, the measurement of the tether's dynamic behavior, as both tension and speed, is necessary, in order to control the vibration of flexible space structures. The range of tension should approach micro level at 10 -2 N in micro power, to control the structure in space. In this paper, the effectiveness of vibration control is examined by employing a tether on a flexible space structures such as a SSPS. The vibration control is analyzed numerically to simulate the behavior of a flexible space structure in a flexible panel-tether system and the effectiveness is shown for the tether tension control. A contactless measurement method is also studied by measuring the tether tension and the speed without contacting tether. This method allows the tether tension to be measured without any disturbance.