The invention discloses a digitization sampling time delay frequency conversion measuring method, and the method measures the non integer period time delay to the different frequency steady state analog quantity signals from an electronic transformer or analog inputting and merging unit to obtain the inertial time delay to all frequency signals from the digitization sampling process, including the non integer period time delay and integer period time delay, compensates the sending time difference for SV message based on the transmit frequency of the phaselock technique tracking SV message, reduces the influence caused by the sending time difference for SV message, and raises the digitization sampling time delay measuring precision. The invention also discloses a test system based on the method for ensuring the reliable application of the electronic transformer and the analog inputting and merging unit in the intelligent substation, eliminating the potential safety hazard of the electronic transformer and the analog inputting and merging unit on engineering application, raising the second-order system running veracity for the intelligent substation and having significance to the safe and reliable operation for the intelligent substation.