Provided is a rapid leakage detecting method suitable for extra-high voltage converter transformers. According to the method, a rapid leakage detecting device is used for detection and comprises a converter transformer used as equipment to be detected, an air compressor used as inflating equipment, a helium gas bottle, a helium mass spectrometer leak detector and a suction gun. A compressed air tank is arranged between the converter transformer and the air compressor, the helium gas bottle is connected with the converter transformer through a pipeline, and the suction gun is connected with the helium mass spectrometer leak detector through a pipeline. The method achieves rapid detection of leakage points of the extra-high voltage converter and is especially suitable for the extra-high voltage converter transformers and also suitable for other large-volume oil-filled transformers.