Lignin, the second most abundant bio-renewable polymer in the world after cellulose, is widely used in industrial production. In recent years, nanoparticles have attracted increasing attention due to their excellent properties. Therefore, the preparation of lignin nanoparticles to obtain value-added products is an effective way to utilize their potential completely. This article describes the preparation methods of micro/nanosized lignin with different sizes and shapes, and provides a detailed introduction to their applications in biomedicine.