The green ammonia preparation system is controlled by a DCS system and comprises a hydrogen production unit and a nitrogen production unit connected with a diaphragm hydrogen-nitrogen compressor. The hydrogen-nitrogen compressor is connected with a circulation machine through an intercooler I, and the circulation machine is divided into two paths through an intercooler II. One path is connected with the reactor through a heat exchanger, and the other path is connected with a buffer tank, and the buffer tank is connected with the reactor; The reactor is connected with the ammonia separator through a heat exchanger, a cooler, a cold exchanger and an ammonia condenser. The ammonia outlet of the ammonia separator is connected with the ammonia storage unit, and the reaction gas outlet is connected with the circulation machine through the cold exchanger. A superheated steam generator connected with the waste heat power generation and distribution unit is arranged in the reactor. The inlet of the superheated steam generator is also connected with a water treatment unit. The waste heat power generation and distribution unit is connected with a new energy grid; the waste heat power generation and distribution unit provides power for the system. This product has low production cost and good safety, can remotely control production, and has a good application prospect.