The correlation of exploration，mining，ore blending，processing and smelting sectors，which are considered to be series- coupled in mine engineering，is considered to be principal for mines. The corresponding geological grade，mining grade，milling grade，concentrate grade，charged grade all plays an important role in the general economical benefits of mines. Based on Five Grades Ganged（FGG）theory，an economic effectiveness model for mining grade benefits was established. The proposed model obeys the principle of ore conservation and metal conservation. Grade-profit activity index was proposed and analyzed via an example. The grade of optimization of a certain metal mine was obtained and the proposed model would establish a foundation for further study of the management mode in mining enterprises.