ZnSe has always been one of the preferred materials for optical parts due to its excellent optical and mechanical properties. The manufacturing cost of optical parts such as optical windows and optical lenses largely depends on the machinability of optical materials, and processing costs account for more than 50% of the total manufacturing costs. The machinability of optical materials is related to the grain size. In this paper, the physical vapour deposition (PVD) method was employed to prepare PVDZnSe infrared optical materials, and the influence of the PVDZnSe preparation process on its grain size and machinability was investigated from the aspects of deposition temperature and raw material properties. It was demonstrated that under the three temperature conditions of 920 ℃, 960 ℃ and 1000 ℃, with the higher deposition temperature, the grain size of the PVDZnSe material showed an increasing trend, and the size ranges were 20-180 μm, 300-2000 μm and 1200-2800 μm, respectively. Under the same process parameters, the PVDZnSe materials were prepared from three different ZnSe raw materials with particle diameters of 2 -10 μm, 10-20 μm and 300-2000 μm. With the increase in grain size of the ZnSe raw materials, the grain size also increased. The results show that the grain size of the obtained PVDZnSe increases significantly, and the brittleness index also increases, which indicates that the machinability of PVDZnSe gradually worsens. The study also found that the influence of grain size on the transmittance of the PVDZnSe material is not significant. The average transmittance of the PVDZnSe material can reach more than 70% in the wavelength range of 2-14 μm. This study provides practical experience and technical support for the application of PVDZnSe optical parts.