Based on the simulation of half-wave current which includes dc component and the experiment on the samples of the participants, the influence on the measurement characteristics of low-voltage current transformer caused by the peak value of half-wave current and dc component is studied in this paper. The experiment shows that the dc component of the current in primary side of low-voltage current transformer would results in the distortion of current in secondary side, and the distortion degree relates to the value of the dc component and also the peak value of current in primary side.