The application discloses a kind of SPWM control's wireless charging systemmetalforeign matter detection device and method, including wireless power transmitting unit, wireless power receiving unit, metalforeign matter detection unit and control unit, the wireless power transmitting unit includes the SPWM modulation circuit, inverter circuit and transmitting coil connected in sequence, the metalforeign matter detection unit includes detection coil group, detection module connected in sequence, the detection coil group is laid on transmitting coil;The detection module includes parallel resonance circuit, high-pass filter circuit and differential amplifier circuit connected in sequence;The detection coil of the application can improve the detection sensitivity of small metal foreign matter.