Abstract: Frequent operation of internal switching devices such as converter valves in the converter station can generate a large amount of high-order harmonics and high-frequency interference, which is one of the main sources of error in DC electronic current transformers(ECT). In order to more accurately grasp the transmission characteristics of DC ECT, the influence mechanism of high-frequency signals on various links of DC ECT is analyzed, a broadband model of DC ECT is built, and the correctness of the model is verified through on-site frequency response tests and step response tests. On the basis of this model, the influence of different device parameters on the broadband transfer characteristics of DC ECT is further analyzed by setting different transformer parameters. The results indicate that the radius of the shunt conductor, residual inductance of the shunt, cutoff frequency of the low-pass filter, type of low-pass filter, and sampling frequency of the merging unit all affect the broadband transfer characteristics of the transformer. Improper parameter selection may result in the accuracy of the DC ECT not meeting the standard requirements. Therefore, comprehensive consideration should be given in the analysis process. The research conclusions have reference value for the parameter selection of DC ECT.