In order to achieve the delay time, rise\fall time of step response of DC Current transformer, and establish the capability of transient characteristic test of DC current transformers, a step response calibration system for DC current transformer based on resampling technology and LabVIEW measurement technology is proposed by analyzing the steady-state calibration technology and transient characteristics of DC current transformer. An experiment for step response characteristics of all optical fiber electronic DC current transformer is conducted in the laboratory, and the experimental results show that the calibration system can accurately measure the transient response parameters such as the delay time and the rise\ fall time of DC current transformer, and effectively improve the screening ability for the performance of DC transformer.