The thermal emission spectrum has found widespread applications in environmental monitoring, astrophysics, medical diagnosis, and drug development. Despite the effectiveness of micro-electro-mechanical system (MEMS)-based infrared emitters in reducing device size, they exhibit drawbacks like a broad spectral distribution range and low emissivity. This paper explores the enhancement of thermal emission characteristics by integrating nanostructures, allowing precise control over spectral features, and effectively improving narrowband emission. The discussion begins with an elucidation of the fundamental principles governing MEMS infrared thermal emission emitters. Subsequently, we delve into the advancements in MEMS infrared narrowband thermal emitters featuring nanostructures such as gratings, photonic crystals, and metasurface structures. The paper further provides a brief overview of the applications of infrared narrowband thermal emitters in gas sensing, thermophotovoltaic power generation, biomedical, and other fields. Finally, a comparative analysis and summary of the performance of nanostructure-based narrowband emitters are presented.