A study on the electronic current transformer has already been entered into practical application， and its verification and the test work have also attracted attention of researchers concerned. Using the measurement uncertainty theory of metrology， the uncertainty source is analyzed， the measurement uncertainty evaluation method for the calibration systems of electronic current transformer is given and implemented with the virtual instrument developed by LabVIEW. An example of the uncertainty comparison of two different calibration systems is given. With uncertainty evaluation to the calibration system it can not only provide the confidence of the measurement result of the calibration system， and used as the science reference for the user， but also can provide comparable parameters for different verification systems.