Abstract: This is anarticle in the field of process mineralogy. The grade of gold and sulfur in a gold mine from Shandong Province was 2.0 g/t and 1.56% respectively, which was a typical gold bearing ore with low sulfur. There covery of gold was made by flotation process in dressing mill, the gold recovery rate was 90%, the gold grade of tailings was 0.17 g/t. To reduce the loss of gold, and improve the flotation performance, MLA（Mineral Liberation Analyser）combined with frequently used process mineralogy method was used to ascertain the reasons for the loss of gold. The study show edpyrrhotite and pyritewere main metal licminerals, feldspar and quartz were a primary gangue miner. The gold locked to gangue and gold included with gangue accounted for 77.29%, of which the size distribution was below 0.01 mm, were difficult to recovered by flotation process. The gold locked or included by metal sulfides and monomer gold accounted for 22.71%, were unreasonable loss. Based on the analysis of process mineralogy of tailings:grinding and classification were the key to further work, which aimed to reduce degree of over grinding of useful minerals, achieve the improvement of beneficiation results.