Abstract: Aiming at the production process of a very fine and lean magnetite ore beneficiation, the ore properties analysis and the comparative experimental researches on key mineral dressing operations were enriched on the basis of the contents of the regular process investigation. Through this process investigation, the problems existing in the production process have been identified, which are mainly manifested in the larger size of ore particles of primary mill feeding, low grinding efficiency of second stage mill, poor magnetic separation effect and large circulation of intermediate products, etc. The results of the process investigation provide the basis for optimizing the operation efficiency and ensuring the rational and efficient production of the mineral processing. It also plays a guiding role in saving energy and reducing consumption, improving operation efficiency and reducing production costs in ore beneficiation production.