Abstract: Based on the experiment on the Shenguang-Ⅱ，the damage of the phosphor and the micro-channel plate of the X-ray framing camera, induced by the vacuum-arc discharge, has been investigated. By measuring the position of the arc on the phosphor and the amplitude of the signal, three kinds of the arc discharges have been distinguished, they are scattered arc, strong arc and fixed arc charges. The damage of the imaging tube and the effect of the working state from the three arc discharges have been compared with different intensity and the different position, respectively. The discharge mechanism is explained with the electron field emission theory, and the stability of the damage is analyzed. The field enhanced coefficient of the fixed arc discharge has been deduced from the experiment result.