Abstract: When a solar array of high voltage is put in low earth orbit (LEO), an arc will be sparked, causing surface degradation, electromagnetic interference and other undesirable side-effects. The mechanism of arcing is discussed, including two theoretical hypotheses and a modified mechanism by Cho and Hastings in terms of the causes, processes and research state-of-the-art. The results of some typical flight experiments and ground simulation experiments are given to show that the arc occurs in LEO plasma environment, and the arc rate has obvious connections with bias voltage. Finally, the advantages and disadvantages of the six methods to mitigate against arcing are discussed.