Abstract: Marginal grade is a grade value which can achieve a certain goal to distinguish between mining and not mining, the production to the factory or the grade of the abandoned after values.Marginal grade index selection is reasonable or not about the fate of the mining enterprises are the important factors that affect mine production decision and economic management.Mine marginal grade is very complex and comprehensive which can be calculated for polymetallic open-pit mine.The influencing factors of marginal grade has several aspects including nature, technology, economy, extraction time, etc.Due to mining the complex internal and external conditions, the marginal grade management is necessarily a dynamic adjustment index.For theoretical analysis of the influential factors of marginal grade polymetallic open-pit mine, help identify the nature of the marginal grade index, the in the volatile market conditions to obtain the optimal operation effect, at the best status of mining enterprise economic management.