The whispering gallery mode(WGM) crystal cavity with a high quality factor and small mode volume has an important application prospect in the fields of optical filters, nonlinear converters, optical sensors and so on. However, the resonant characteristics of exposed optical microcavities are easily influenced by the external environment. In this paper, the coupling and packaging technology of the tapered fiber and the WGM micro-cavity based on the magnesium fluoride crystal is studied. The tapered fiber is prepared by oxyhydrogen flame, and the diameter of the taper waist is about 2 μm. An experimental platform for testing the coupling quality between micro-cavity and tapered fiber is set up. Only a few modes in a specific wavelength range are observed in the optimized the fiber coupling system, and the quality factor reaches 5.15×107. Furthermore, a coupling and packaging system with accurate temperature control is built to improve the stability of the coupling system. A useful idea is provided and realized for packaging ultra-high quality WGM crystal cavities from the perspective of practical application.