The invention provides a transformer neutral conductor virtual connection fault detection method. The method comprises steps that after a transformer has a fault, a neutral conductor virtual connection detector is used to measure the phase voltage of each of three phases L1, L2 and L3 of a to-be-measured power distribution network, wherein the neutral conductor virtual connection detector comprises a digital multimeter, an image identification unit, a control unit, an alarm unit and a display unit; that the phase voltages of the three phases L1, L2 and L3 are repeatedly detected by disconnecting a breaker and neutral conductor grounding; that the neutral conductor virtual connection detector analyzes and compares the phase voltage of the three phases L1, L2 and L3 and analyzes and determines whether the transformer has a neutral conductor virtual connection fault or not; and that a fault alarm can be sent by the alarm unit and displayed by the display unit, and the neutral conductor is maintained and the virtual connection fault is tackled. The fault detection method is simple and convenient, and easy to operate. A universal meter is clamped in the detector, and is easy to maintain and replace. Automatic comparison of phase voltage data is achieved by a control center. The detection values and the fault detection result can be timely displayed.