With the rapid development of intelligent technology, micro-control system plays an important role in key fields such as energy, aerospace, high-speed rail and nuclear facilities by virtue of its high precision, high reliability and modular design. In this paper, we systematically sort out the application status and technical progress of micro control systems in the above fields, focusing on the analysis of typical application cases such as transformer cooling control based on microcontroller, adaptive control of turbine speed and pumping pressure, attitude control of aircraft, high-speed rail auto-pilot, radiation monitor, etc., and discussing the development trend of the direction of its intelligentization and miniaturization. The study shows that the in-depth application of micro-control system will promote the further development of industrial automation, energy efficient utilization and intelligent equipment. At the same time, according to the research, the application suggestions of micro control system in the field of nuclear facilities are given to improve the economy and intelligence of control system in the field of nuclear facilities.