Combining hydrogen production from renewable energy with traditional chemical processes to achieve electric-hydrogen-chemical coupling can not only improve the utilization of renewable energy, but also facilitate the green and low-carbon transformation of chemical processes. Aiming at the contradiction between the fluctuation of renewable energy and the stability of chemical process in electric-hydrogen-chemical coupling system, an optimal configuration model was established, including large-scale wind-solar complementary power generation, hydrogen-storage, and ammonia synthesis system. The influence of key parameters such as wind-solar ratio, hydrogen production capacity, minimum hydrogen production load and hydrogen storage tank volume on system operation was studied, the instantaneousoperation characteristics of the system throughout the year was analyzed. The results show that when the wind-solar ratio is around 8 ∶ 3and the hydrogen production capacity is close to the wind-solar average output power, it is more likely to reduce the grid supply under thesmallest storage tank volume. The decrease of the minimum load of hydrogen production and the increase of the volume of the storage tankare conducive to the increase of the stability of the system and the decrease of the grid power supply, which was expected to realize thepure green power operation of the system. When the system parameters are configured as the wind-solar ratio of 8 ∶ 3, the hydrogen production capacity of 400 MW, the minimum hydrogen production load of 20% and the hydrogen storage tank volume of 100 000 m3, the annual average grid power supplement ratio is about 5%. The simulation results of 8 760 h system operation show that the regulation of hydrogen production load can slow down the system fluctuation. And then ammonia synthetic equipment can continuously operate in the range of50%-110% with hydrogen storage tank buffer.