The cesium atomic fountain clock is a standard frequency signal generation device based on the internal quantum transition of atoms and is currently the universal frequency standard. The ultra-low temperature cesium atomic fountain clock is a special type in which cesium atoms operate at liquid nitrogen temperature(80 K), which effectively reduces the blackbody radiation frequency shift to less than 1×10-16, nearly eliminating the influence of this shift. The cavity phase frequency shift and background gas collision frequency shift of the cesium atomic fountain clock will be greatly improved, with the potential to reduce the systematic frequency uncertainty of the cesium atomic fountain clock to below 2 × 10-16. The magnetic shielding device is an important part of the physical system of the fountain clock. The performance of the magnetic shielding device affects the magnetic field frequency shift and uncertainty index of the fountain clock. Since a liquid nitrogen Dewar interlayer is set on the periphery of the resonant cavity and the atomic flight area, the liquid nitrogen inlet and outlet pipes need to penetrate multiple layers of magnetic shielding. The magnetic shielding structure of the ultra-low temperature cesium atomic fountain clock is more complex than that of the room temperature fountain clock, and the development difficulty is greater. In this paper, according to the spatial structure and application requirements of the ultra-low temperature cesium fountain clock, a corresponding magnetic shielding device is designed. The optimal parameters such as the number of layers, thickness, size, and interlayer spacing of the magnetic shielding device are determined by simulation calculation. The magnetic shielding device is processed according to the design. The processed magnetic shielding device is subjected to high-temperature demagnetization and AC demagnetization treatment. After testing, the radial magnetic field change in the core area of the magnetic shielding device is less than 0.1 nT, the axial magnetic field change is less than 1.3 nT, the shielding factor at both ends is greater than 10 000, and the central shielding factor is greater than 60 000, which meets the application requirements of the ultra-low temperature cesium atomic fountain clock.