Abstract: With the continuous construction of UHV transmission lines in China, the problem of long insulator string ice flashover in icing area is becoming more and more prominent. However, the research on the motion characteristics of ice arc is rarely available in the literature, thus the flashover mechanism of long string of iced insulators is unclear. In order to solve the shortcomings of the existing research, local arc tests were carried out with ice column in the multi-functional artificial climate chamber, and the generation and development processes of DC local arc were captured using the ultra-high speed camera in this paper. The results show that, compared with the negative local arc, the generation of positive local arc requires lower voltage and longer time. It is found that there are many discharge branches with different lengths and diameters between the arc foot and the ice surface, which diffuse from the center of the arc foot to the surrounding. During the development of DC ice surface arc, there are two kinds of discharge forms, namely, arc column to arc column discharge, and arc column to ice surface discharge, and their discharge directions are opposite.