Metal transfer mode of the low hydrogen type structural steel covered electrode is the one that coexists as the globular short-circuiting transfer and the fine droplet transfer in the flux-bridge. Component of the metal transfer modes has a direct effect on usability of the covered electrode. The oscillograms of the arc voltage and the welding current gained using the traditional photoelectric oscillograph can only qualitatively describe the general characteristics of metal transfer, but can’t make a quantitative analysis. Using the ANALYSATOR HANNOVER, the welding electrical parameters are measured and analyzed. Four characteristic information values correlated with usability of the covered electrode, such as the frequency of the globular short-circuiting transfer, the globular short-circuiting time, the mean value of the globular short-circuiting time and the mean value of the weighted arcing time, are extracted. The method of principal component analysis is applied to determining the evaluation index for usability of the covered electrode. Thereby quantitative evaluation for usability of the covered electrode is realized. A new method is offered for scientifically evaluating usability of the low hydrogen type structural steel covered electrode.