In recent years, the semiconductor and optical manufacturing sectors have seen rapid advancements, driving a growing demand for thin flat components such as wafers, optical windows, and sealing rings. As a result, the quality requirements for processing these components have become increasingly stringent. Double-sided lapping has emerged as a widely used technique for processing thin flat components, owing to its low processing stress and high efficiency. This chapter aims to provide a comprehensive overview of the current state of double-sided lapping, focusing on the mechanisms, processes, applications, and recent advancements in related equipment. Additionally, it analyzes the optimization effects of theoretical models on the double-sided lapping process, offering an overview of its current applications. This analysis serves as a valuable reference for future research and projects potential development trends in double-sided lapping technology.