China has proposed the “dual-carbon” goals and supported the realization of the goals by planning and building a new energy system. Renewable energy has a high proportion in the new energy system, and its intermittency and difficulty in scheduling determines that the new energy system needs large-scale flexibility to support the power supply. Both natural gas and hydrogen have the multiple characteristics of being clean and low-carbon, flexible, convertible, and easy to store and transport, which determines that they will inevitably play a key supporting role in the new energy system. This paper analyzes the characteristics of China's new energy system, discusses the role of natural gas and hydrogen energy in different stages of the development of China's new energy system, and puts forward suggestions for the development of natural gas and hydrogen energy.