A magnetic sensor is provided with a magnet and a magnetic sensitive element, the magnetic sensitive element responses to a magnetic field generated by a magnetic code in a banknote which is magnetized by the magnet, the whole or part of a hysteretic loop process is completed when the magnetic code is magnetized by the magnet while passing by the surface of the magnetic sensor. A method for quantitatively identifying magnetic hysteresis loop characteristics of magnetic code, the whole or part of the hysteretic loop process is completed when the magnetic code is magnetized by the magnet while passing by the surface of the magnetic sensor, the magnetic sensor reads the signal of the corresponding magnetizing process, and then soft magnetism and hard magnetism properties of the magnetic code on the magnetic hysteresis loop characteristics of the magnetic code are identified.