This book gathers the proceedings of the 4th International Conference on Mechanical Engineering and Applied Composite Materials (MEACM), held in Beijing, China on October 24-25, 2020. The conference brought together researchers from several countries and covered all major areas of mechanical engineering and applied composite materials, new applications and current trends. The topics covered include: structure and design, mechanical manufacturing and automation, robotics and mechatronics, mechanical behavior of nanomaterials, nanocomposites, and composite mechanics. Given its scope, the book offers a source of information and inspiration for researchers seeking to improve their work and gather new ideas for future developments.