Abstract: In response to the issue of inconsistent coating appearance caused by uneven gas distribution during the industrial mass production of PVD-coated tools, this study conducted simulation and experimental optimization of a uniform gas distribution structure in the cathode system of PVD coating equipment. Using a single-tube nozzle-type gas distribution pipeline as the research object, a three-dimensional fluid simulation model was established to investigate the effects of two different gas distribution methods—equal hole spacing and gradually varied hole spacing—on the flow field characteristics of the working gas. The results indicate that by adopting a gradually decreasing hole spacing configuration in an arithmetic sequence, the gas flow velocity deviation among the outlets can be controlled within 5%, thereby significantly improving the uniformity of gas distribution. Furthermore, to mitigate the negative effects caused by the orifice jet flow, the structure was optimized by orienting the gas outlets downward, which effectively enhanced gas diffusion and mixing. Experimental validation was carried out using a self-developed LIP1400 multi-arc ion plating system for TiCN coating deposition. EDS analysis revealed that the carbon content deviation in the coatings on tools positioned at the upper, middle, and lower levels of the chamber was less than 10%, while the visual appearance changed from an initial gradient of tan–rose gold–light yellow to a consistent and uniform rose gold color. This study demonstrates that the optimized gradually varied hole spacing structure, based on flow field simulation, can effectively enhance the axial deposition uniformity of PVD coating on tools. The proposed method is straightforward to implement, requiring only modifications to the gas distribution pipeline without the need for complex symmetrical structures or high-precision assembly. It is therefore highly suitable for the technical upgrading of existing equipment and holds significant potential for industrial application.