Abstract: Preparation course and wire properties of ultra-fine W wire with modulation diameter were studied by using the preparation device, laser-diffraction device for on-line diameter measurement, and the SEM and mechanical property test. It was showed that alternate of electrolyzation voltage and zero voltage could be a feasible way for preparing continuous W wire with modulation diameter shape. The modulation shape of W wire was obvious in the system of (100-500) gL-1NaOH electrolyte with 1.4 V and 1.6 V voltage. Corresponding modulation shape could be achieved in NaOH electrolyte of concentration less than 500 gL-1, when electrolyzation voltage was high. The relationship of direct ratio between loss weight of tungsten wire and the product of current intensity and electrolyzation time in the preparing process of ultra-fine tungsten wire by electrochemical corrosion technology was deduced and examined. The value of direct ratio could be 5.3510-5gC-1 in some certain condition. The thick segment diameter was 12.2 m, the thin segment diameter 9.8 m, and the ratio of diameter reduction was about 20% with experiment parameters of electrolyte density of 200 gL-1, a voltage of 2.0 V and an electrolysis time of 3 s. Fracture force of such modulation W wire was 0.2883 N.