Numerical simulation, also known as computer simulation, uses an electronic computer to investigate and solve engineering problems, physical problems, and a wide range of other problems through numerical calculations and image visualization methods. Numerical simulation is often employed to support machine design, parameter selection, and size optimization, enabling the comparison of various schemes and processes. In recent years, numerical simulation has emerged as a powerful and promising tool for studying drum drying processes. Its applications include understanding complex gas–solid fluidization properties, exploring potential mechanisms of gas–solid flow, and optimizing drum drying design and scaling. This paper comprehensively reviews the numerical modeling of gas–solid flow, focusing on the numerical simulation of the flow characteristics in the drum drying process. Moreover, it identifies current challenges and outlines future development trends in the numerical simulation of this drying process, providing valuable insights for the optimization and application of this simulation technique in the broader field of drying technology.