In this work, we propose a whispering gallery mode (WGM) resonator filled with Terfenol-D (WGMRFT), which can be applied to magnetic field sensing and tuning. We used a hollow quartz rod to fabricate the resonator, and then filled it with Terfenol-D to create a magnetic field-sensitive device. The WGM of the resonator were excited using a tapered fiber evanescent field. As the external magnetic field increased, the WGM resonant spectrum of the resonator shifted toward the short wavelength direction. The sensitivity of the resonator is -3.05pm/mT. The structure has many advantages, such as simple structure, low cost and easy operation. In addition, we have demonstrated a resonator coupling and packaging device, using this device to adjust the coupling state of the resonator within a certain range. The package demonstrated good repeatability and reversibility in magnetic field measurement experiments. This lays the foundation for the application of millimeter-scale large WGM resonators.