A detector capable of detecting bearing faults in advance is disclosed. The detector includes a microprocessor with an input terminal connected to a power supply and an output terminal connected to a detection information output device. A resonance enhanced piezoelectric sensor is provided. A sensor trigger detection circuit is electrically connected between the sensor and the microprocessor. An input terminal of the sensor trigger detection circuit is connected in parallel with a sensor signal selection circuit. The sensor signal selection circuit is connected in series with a sensor signal processing circuit. An output terminal of the sensor signal processing circuit is connected in series with a programmable gain circuit. The programmable gain circuit is connected to the microprocessor. The sensor trigger detection circuit, the sensor signal selection circuit, the sensor signal processing circuit, and the programmable gain circuit are respectively connected to the power supply.