According to the statistics of advanced repairs for high-speed EMUs, rust and peeling are the main faults in bearing system. At present, there are two kinds of bearing fault monitoring systems for high-speed EMUs, i.e., on-vehicle shaft temperature monitoring system and TADS trackside acoustic diagnosis system, which have high accuracy for the determination of faulty bearings, but also have their own limitations to a certain extent. Aiming at the abnormal bearing problems of high-speed EMUs that not detected by both the on-vehicle temperature monitoring system and the TADS trackside acoustic diagnostic system, the vibration test by the transmission monitoring system and the noise test by the portable noise equipment were carried out, and by using FFT, STFT and other technical means to identify the fault frequency, the fault source was found out, which should provide important help for the axle box bearing fault diagnosis.