The invention provides a method and a device for flaw detection of a train wheel set. The method comprises the following steps: extracting data graph information of the train wheel set from a flaw detection data after packaging; analyzing the data graph information, thereby acquiring a reflecting wave with a reflecting wave amplitude value of the train wheel set not less than a first threshold and taking the reflecting wave as an initial defect waveform; and taking the initial defect waveform acquired by a normally working flaw detection part screened out from the initial defect waveform as a target defect waveform, thereby removing the initial defect waveform with ultrahigh reflecting wave amplitude value of the train wheel set caused by the abnormal condition of the flaw detection part, and ensuring that the position of the train wheel set corresponding to the target defect waveform is the real flaw position based on the incidence relation between the reflecting wave and the train wheel set information. According to the method provided by the invention, the analysis for the online high-speed collected and packaged flaw detection data is realized and the flaw position of the train wheel set is accurately judged, so that the safety and reliability of the train running are ensured.