Taking the traditional cemented carbide WC-10Co-0.6Cr₃C₂ (wt%) substrate as the reference object, WC-10Co-0.4TiC-0.6Cr₃C₂ (wt%) plate-grained cemented carbide tools were prepared by Ti induction method, and PVD-TiN/AlTiN nano multilayer composite coatings were deposited on the surfaces of the two groups of tools. The milling behavior of two coated tools in the machining process of 316L stainless steel was studied. The results show that under dry milling, the main failure mode of tools are wear and edge collapse, and the milling life of PT tool (based on the plate-grained cemented carbide) is 48% longer than that of CT tool (based on the traditional cemented carbide). Under wet milling, the main failure modes of tools are coating peeling and edge collapse, and the milling life of PT tools is 41% higher than that of CT tools. Under both dry and wet milling conditions, the first macro thermal crack time on the surface of PT tool is later than that of CT tool. PT tool has a longer wear stability period in the milling process. Its excellent ability to resist crack initiation and propagation is an important reason for the improvement in the milling life of coated tool (PT) based on plate-grained cemented carbide.