The global warming problem caused by the massive combustion of fossil fuels and the release of carbon dioxide is receiving increasing attention. Therefore, renewable energy sources such as wind and solar energy are developing rapidly now. Renewable energy electrolysis of water for hydrogen production and ammonia synthesis has great potential for development, and the existing Haber–Bosch process requires high temperature and pressure and emits a large amount of carbon dioxide. In this chapter, we introduced a plasma synthesis technology for ammonia at room temperature and pressure. The chapter started with the background and current situation of ammonia synthesis, elaborated on the concept and technological advantages of plasma, summarized the principle and case of plasma synthesis of ammonia, summarized the case and mechanism of plasma-combined catalyst synthesis of ammonia, analyzed the dynamic simulation of plasma synthesis of ammonia and described the process of plasma decomposition of ammonia.