The by-produced gas, waste heat, and steel slag as well as the current situation on the co-production of steel and chemical in the iron and steel industry are analyzed. The developing trend of green and low-carbon technologies is discussed and the new mode from "carbon fixation by chemical" to "carbon substitution by hydrogen" in carbon-free steelmaking in the future is prospected. Suggestions and measures are put forward to the application of new technologies for steel and chemical co-production. It is expected to establish a new sustainable industrial ecosystem with the steel industry as the leader coupled with the chemical industry to support the realization of China's carbon peaking and carbon neutrality goal.