The reactor pressure vessel head (RVH) is a typical radioactive waste in the decommissioning of nuclear power plants. Its decommissioning process is complex and technically challenging, requiring comprehensive consideration of multiple factors such as optimization of collective dose, minimization of waste, industrial safety, and management of decommissioning costs. Due to the lack of relevant engineering experience in China, this paper takes the RVH replaced from the Daya Bay Nuclear Power Plant as the research object and uses digital simulation technology to optimize its decommissioning process. To this end, a general decommissioning design platform based on Decommissioning Information Modeling (DIM) technology has been developed, which can flexibly import work scenarios and freely set the properties of processing equipment, reducing the difficulty of multi-scheme simulation. Through the DIM platform, the research team imported RVH processing equipment, radiation field data, and work plans to simulate the decommissioning process of the RVH and obtained key information including personnel dose, engineering progress, waste quantity, and decommissioning costs. In the study, two different cutting schemes for the CRDM nozzle seat were designed for simulation, and the differences in waste quantity, collective dose, and cost between the two were compared. The simulation results provide data support for optimizing the RVH decommissioning plan and are helpful for the implementation of similar decommissioning projects in the future.