The utility model discloses an online intelligent oil-recharging device of an electric transformer. The online intelligent oil-recharging device comprises an oil storing tank, a variable frequency oil-filling pump, a tee pipe and a control module, wherein the oil storing tank is provided with an oil-outlet valve; an oil-outlet electromagnetic valve, an oil-discharging valve and a pressure sensor with pressure limit control are arranged on the tee pipe; the inlet of the variable frequency oil-filling pump is connected with the oil storing tank; the outlet of the variable frequency oil-filling pump is connected with the tee pipe; the oil-outlet electromagnetic valve is arranged on the outlet end of the tee pipe and is connected with an oil-filling valve of the electric transformer through an external connecting pipe; the oil-discharging valve is arranged on a side branch pipe of the tee connecting pipe. The online intelligent oil-recharging device of the electric transformer can work on the ground without power outage and ascending. Compared with the traditional oil-recharging way, the online intelligent oil-recharging device has incomparable advantages.