The invention discloses a rapid testing apparatus and testing method for large scale transformer's direct current resistance. The apparatus comprises a high voltage side testing module and a low voltage side testing module. The high voltage side testing module comprises current sampling resistors RN. The winding in star connection in each phase of a transformer is connected in series with the corresponding current sampling resistor RN. Each current sampling resistor RN and a resistor RX in the corresponding tested winding form a series connected voltage dividing circuit. The voltage testing model in each phase is connected to a voltmeter and the series connected voltage distributing circuit is in series connection to a constant current source. The low voltage testing module comprises a controller, a multi-channel relay and a current and voltage testing module. The controller is connected to the relay and the current and voltage testing module. The two ports of each channel of the relay are connected to the A-phase, B-phase and C-phase windings in star connection at the high voltage side of the transformer, the a-phase, b-phase and c-phase windings in delta connection at the low voltage side of the transformer, and a power supply. The controller is further connected to a display screen. According to the invention, the testing apparatus and the testing method can achieve accurate experiment data, reduce work risk, raise work efficiency and ensure the safety of both people and equipment.