Metalenses have recently attracted increased attention due to their remarkable characteristics. The fabrication technology of metalenses has also become an important research direction. In this study, we propose a metalens structure based on Au–MgF2–Au in infrared waveband. The preparation process of the metalens included magnetron sputtering, electron beam evaporation, and electron beam exposure. A dose test was performed during the exposure process, adjusting the exposure dose to minimize the proximity effect after exposure. Then, SEM was used to measure the processed metalens structure, and FDTD software was used to build a model based on the metalens, simulating and analyzing its focusing characteristics. The results show that the size deviation produced during the processing has little effect on the functionality of the metalens. The processed metalens can also focus different polarized light incidences at different spatial positions: The metalens can focus at 4.97 μm for x-polarized light and focus at 13.5 μm for y-polarized light. Additionally, the metalens has good focusing effects with different working wavelengths. We believe that the processing method of metalens proposed in this paper provides guidance for the preparation of subwavelength metasurface structures, and our findings are beneficial in developing new methods of near-infrared regime manipulation.