GeTe belongs to a type of chalcogenide phase change materials, which can dynamically achieve reversible switching between the crystalline state of low resistivity and the amorphous state of high resistivity by utilizing the thermally induced phase change characteristics. GeTe is an important functional material in the fields of memristors and nonvolatile RF switches. As for RF switch applications, this paper focuses on the electrical performance optimization of GeTe thin films prepared by magnetron sputtering. By comprehensively analyzing the effects of substrate materials, sputtering conditions, and annealing conditions on the resistivity of crystalline GeTe films, effective preparation conditions for low resistivity GeTe films are explored. Figure (a) shows that compared with the GeTe film on the SiO ₂substrate, the film on the Al ₂O ₃substrate can obtain higher crystallinity and lower resistivity. For the deposition power and pressure in figure (b), the combination of medium power (50-80W) and low pressure (2-3mTorr) is beneficial for low crystalline resistivity of GeTe film. Additionally, figure (c) shows higher annealing temperature (350-400℃) is able to realize lower film resistivity. Finally, the experimental results have showed that the lowest crystalline resistivity of the prepared GeTe thin film reaches 3.6×10 ^-6Ω· m, and the resistance ratio is more than 10 ⁶. Based on rectangular chips of GeTe film, a parallel millimeter-wave switch with zero static power is also constructed. As shown in figure (d), the insertion loss is less than 2.4dB, and the isolation is greater than 19dB in the 1-40GHz frequency band, demonstrating the potential application of GeTe thin films in the field of broadband high-performance discrete nonvolatile RF switches.