The influence of residual charge on propagation of surface discharge is experimentally investigated using high-speed framing and streak cameras, and an electrostatic probe. When consecutive impulse voltages are applied 25 times with a change in polarity, the propagation length of the surface discharge increases gradually from 79 to 164 mm and hardly converges. Under such a condition, the potential gradient in the surface leader channel decreases with the consecutive number of impulses, while that in the surface streamer remains constant and the value is 0.5-0.6 kV mm~(-1). With the residual charge of a previous opposite polarity discharge on an insulator, the propagation velocity increases to three to eight times as large as that of the surface discharge on a clear insulator without any residual charge. The peak current of the surface discharge with a residual charge also becomes much higher than that without a residual charge.
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