Abstract: High-temperature superconductors predominantly exhibit layered lattice structures, and thus the study of epitaxial thin films and heterostructures, which inherently possess low-dimensional properties, has become a major method for exploring the mechanism of superconductivity. In recent years, the development of atomically precise epitaxy has further facilitated the discovery of novel superconductors. This article will follow a dimensionality reduction trajectory to explore the unique contributions of high-temperature superconducting thin films and heterostructures in deepening our understanding of the mechanism underlying superconductivity.