Study on the electronic current transformer transient transmission delay problem from the application of relay protection angle. Explain the difference between transient delay time and steady state delay time, as well as the necessity test in engineering. Proposed a test scheme based on simulation sampling with high accuracy and high bandwidth, and the precise time scale digital calibration receiver. Using the digital phase locked loop (DPLL) to eliminate the digital timing jitter. Using mutation detecting to determine the initial time, combined with the phase extraction for time delay compensation. The various error factors have been eliminated in the test well. Through the application of the developed test system in engineering, proved the feasibility of the scheme.