Abstract: Ammonia is a core raw material in the nitrogen fertilizer industry and an important potential energy carrier. The currently widely used Haber-Bosch ammonia synthesis process relies on fossil energy and has problems such as high energy consumption (accounting for 1-2% of global energy consumption) and large carbon emissions. The process conditions are also strict (requiring 400-500℃ and 10-25 MPa). Against the backdrop of energy transition and carbon neutrality, the H2-based chemical looping ammonia synthesis (H2-CLAS) technology has unique advantages. Compared with traditional processes, H2-CLAS avoids the competition for adsorption between nitrogen and hydrogen through the recycling of nitrogen carriers, reduces the operating pressure and temperature requirements. This decoupling strategy reduces energy input, improves raw material utilization, and has distributed and miniaturized characteristics, which can be combined with intermittent renewable energy and flexibly adjust the production rhythm, making it a current research hotspot. This review systematically