The utility model provides an online calibration system of electric energy meter. This system includes the collection equipment of front end, the pre treatment device of rear end, digital electric energy meter check gauge and main website, and wherein, the data network that collection equipment passes through electric power links to each other with pre treatment device, pre treatment device links to each other with digital electric energy meter check gauge and main website. Tradition voltage transformer's secondary side voltage, traditional current transformer's secondary side electric current insert simultaneously and are examined electronic type electric energy meter and collection equipment, the digital voltage current sample value of merging cells or switch inserts is simultaneously examined digital electric energy meter and collection equipment, the pulse output of electric energy meter inserts collection equipment. The utility model discloses an online check -up of tradition transformer substation electronic type electric energy meter and the digital electric energy meter of digital transformer substation has realized the long -range real -time on -line monitoring and online check -up of electric energy meter each item index, has solved not enough that present mode existed. The utility model discloses simple structure, thought are leading, and the system is with low costs, accords with metering device's development trend. Simultaneously, change current mode, improved work efficiency.