Abstract: Decarbonization is a critical issue for peaking CO₂ emissions of energy-intensive industries, such as the iron and steel industry. The decarbonization options of China’s ironmaking and steelmaking sector were discussed based on a systematic three-dimensional low-carbon analysis from the aspects of resource utilization (Y), energy utilization (Q), and energy cleanliness which is evaluated by a process general emission factor (PGEF) on all the related processes, including the current blast furnace (BF)–basic oxygen furnace (BOF) integrated process and the specific sub-processes, as well as the electric arc furnace (EAF) process, typical direct reduction (DR) process, and smelting reduction (SR) process. The study indicates that the three-dimensional aspects, particularly the energy structure, should be comprehensively considered to quantitatively evaluate the decarbonization road map based on novel technologies or processes. Promoting scrap utilization (improvement of Y) and the substitution of carbon-based energy (improvement of PGEF) in particular is critical. In terms of process scale, promoting the development of the scrap-based EAF or DR–EAF process is highly encouraged because of their lower PGEF. The three-dimensional method is expected to extend to other processes or industries, such as the cement production and thermal electricity generation industries.