With the continuous increase in power density of power electronic devices, thermal simulation analysis of air-cooled heat sinks has become an indispensable technical tool in product design and development. This paper systematically reviews the typical workflow and key technical procedures of thermal simulation methods for air-cooled heat sinks, including geometric modeling and model simplification, material thermophysical property assignment, computational domain mesh generation strategies, boundary condition and solver configuration, as well as result post-processing and identification of thermal weak links. On this basis, the main application scenarios of thermal simulation in air-cooled heat sink design are summarized, encompassing thermal performance evaluation, parameter sensitivity analysis, and heat source layout optimization. The analysis indicates that the accuracy of fluid-solid coupled modeling and mesh quality are the core factors affecting simulation reliability, while downstream hot air accumulation in unidirectional parallel-flow air cooling structures is a typical issue constraining the temperature uniformity of multi-chip modules. This paper also discusses the complementary relationship between simulation and experimental validation, and proposes directions for future methodological improvements, aiming to provide references for thermal simulation analysis and design optimization of air-cooled heat sinks.