To fabricate a high-sensitivity fiber magnetic field sensing probe based on a Fabry- Pérot interferometer, an arc magnetic polymer thin film was integrated on the end face of a single-mode fiber using the UV curing method. Strip magnet was used as the field source to modulate the cavity length and refractive index of the interferometer. By monitoring the wavelength position of the interference peak, the magnetic field intensity was detected. The magnets were placed vertical and parallel to the sensing probe, and the corresponding sensitivities of the sensing structures were 46.77 pm·mT ^-1 and 56.37 pm·mT ^-1. The sensor has high sensitivity, good stability, and wide application prospects in the various fields, including biological medicine and information technology. Further, the sensor is inexpensive and can be conveniently manufactured.