A high stable wire transport system of wire-cut electrical discharge machine (WEDM) that can exercise the micro-wire machining is developed in this paper. In the wire transport system, two novel designs are proposed to improve wire tension variation during machining. 1. Active wire feeding unit: a device is used to isolate the inertia of the wire reel from the wire transport system. Hence the inertial loading of the wire can be reduced and the stability is also increased. 2. Multilayer sandwich vibration absorber: the axis of the reel is connected to a damped sandwich beam. When the perturbation occurs, the flexible motion of the beam can absorb the fluctuation of the wire. Then the wire tension can be more stable and better working precision is also achieved. Finally, two mechanisms were implemented on a micro wire-EDM machine to suppress the fluctuation of wire tension. Experimental results show that the variation of wire tension can be significantly reduced from 12.4 gf to 5.5 gf.