Abstract: The classic mathematical model of multi-metallic mass balance fully respected  the concentrate grade in testing, bur ignored the reasonability of adjusted raw ores' and tailings' grade.In view of these disadvantages, this classical mathematical model was upgraded and improved.The upgraded mathematical model takes into account the grade of raw ores, concentrates and tailings.The grade analysis of each product is more systematic and comprehensive, making it closer to the actual adjustment.So after adjustment, the results are more scientific, rational, reliable, which can meet the needs of the index adjustment for beneficiation.

Key words: Metal mass balance, Mathematical model of mineral processing, Beneficiation