With the advent of 5G era, the demand for high frequency, high temperature, high power, high energy efficiency, harsh environment resistance and miniaturized power semiconductor devices is increasing rapidly. At the same time, with the increase of base station channel number and communication radio frequency, MEMS (Micro-Electro-Mechanical System) is one of the related technologies for this trend. The 12th China International Nanotechnology Industry Expo will be held in Suzhou, Jiangsu Province from October 27th to 29th, 2021. Among the many symposiums, the one on the key technologies and processes of compound semiconductors and piezoelectric thin film devices will be sponsored by the Bureau of Personnel Chinese Academy of Sciences, Jiangsu Nanotech Industry Innovation & Development Center, and organized by Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), CAS. The symposium will invite well-known nanotechnology professionals from universities, research institutes and enterprises to teach relevant knowledge, especially on the processing, testing and analysis of compound semiconductor power electronic devices and AlN MEMS devices. This symposium is intended to provide an opportunity for communication in the related research and development fields.