Abstract: Schematic description on theory of multi-dimensional mass flow control (MMFC) in Iron & Steel manufacturing process is proceeded from four aspects which are meaning, concept, research content of MMFC system in Iron & Steel manufacturing process and research base of MMFC in steelmaking plant.Applied the theory to high efficiency continuos casting, process analysis and synthetic research on all working procedures in converter plant are carried out, integrated optimization of various working procedures and their relationship in producion process is realized, and enormous economic benefit is obtained under the guide of global optimization principle.