Abstract: The evolution of single-wire and dual-wire electrical explosion of 8 m- and 10 m- W was investigated by X-ray backlighting using the X-pinch as a soft X-ray source. The experiments were carried out on the pulsed power generator PPG-1 (400 kA/500 kV/100 ns) which was designed and constructed by Department of Electrical Engineering of Tsinghua University. The X-pinch as the X-ray source and the tungsten wire as the object are installed between the anode and the cathode and in the place of a current-return rod, respectively. The X-ray films of high resolution and high sensitivity were used to record the results. The current sensor and Rogowski coil of our own design were used to monitor the current. In order to observe the evolution of mass density distribution of the electrical explosion of single-wire of tungsten, the step wedge was designed. By a large number of imaging experiments, the physical images of wire core expansion, the formation and outward diffusion of the coronal plasma and the mass density distribution based on the original film were obtained. The conductance of 8 m-W was also calculated using voltage and current data.