The utility model relates to a device for suppressing direct current at a neutral point of a transformer by during high voltage power transmission and transformation, in particular to a device for suppressing direct current at a neutral point of a transformer by an adjustable resistor method. The device for suppressing the direct current at the neutral point of the transformer by the adjustable resistor method comprises an adjustable resistor circuit, a status changing-over switch circuit and an overvoltage bypass circuit, wherein the adjustable resistor circuit, the status changing-over switch circuit and the overvoltage bypass circuit are connected in parallel with one another and then connected in series between the neutral point of the transformer and a grounding electrode; and the adjustable resistor circuit is in a range from 0 to 4 Ohms. By the device, series resistors at the neutral point of a direct current transformer blocks direct current at the neutral point, so that a resistance value can be set to suppress direct current at the neutral point of the transformer, a phenomenon that parameters of other equipment are required to be adjusted to match with the resistance value can be avoided, and particularly all relay protection setting values are not required to be reset. When the status changing-over switch circuit is in a breaking status, the neutral point of the transformer is grounded through the adjustable resistor circuit, so that the current at the neutral point of the transformer is blocked. The device for suppressing the direct current at the neutral point of the transformer by the adjustable resistor method is simple in structure and high in reliability, and reliability of starting an overvoltage bypass is improved.