This book presents the proceedings of the 2021 International Symposium on Automation, Mechanical and Design Engineering (SAMDE), held in Beijing, China, on 3–5 December 2021, and organized by the Hong Kong Society of Robotics and Automation (HKSRA). It gathers contributions by researchers from several countries on the following topics: digitalized development and use of sustainable products and manufacturing systems, artificial intelligence, automated reasoning, human-robot collaborative interaction, sensors and autonomous sensor systems, cyber-physical control systems, generative design including topology optimization, advanced simulation and modelling, intelligent automation, smart materials, materials processing and factories, and circular economy, etc. The book offers a source of information and inspiration for researchers seeking to improve their work and gather new ideas for future developments.