This paper briefly introduces two experimental methods of transformers test set and voltage ampere phase, secondary burden of work stations is measured in the metering current transformer automatic testing system. The result shows that the wire resistance is more than 60mΩ on average,100 mΩ up to the max resistance value and most of relative errors between the actual burden and the nominal burden exceed 5% , 19% up to the max relative error while the volume of the burden box is 2.5VA. The fact that contact resistance of relays and poor contact between terminals of current transformer and connection mechanism is the main reason. It analyses influences on secondary burden and error of current transformer. Finally, some improvement measures are suggested for the system. This decreases secondary loop impedance and improves the test quality of current transformer.