Cobalt refinery production mainly uses rough-wrought Cobalt carbonate or Cobalt hydroxide as raw material. In recent years, with the increasing complexity of raw ingredients, the filtering of leaching solution by leaching cobalt raw material has become increasingly difficult, which has become an important factor in the normal production of the cobalt refining. In this paper, the technology of improving the filtration performance is discussed, by adding sodium sulfite as reducing agent and sodium carbonate with regulating pH value, the Fe (OH) 3 with positive charge is formed in leaching solution, which attracts silica sol with negative charge each other to generate big molecule. This technology realized high efficiency filtering production of high raw cobalt salt leaching liquor and remove impurities by adsorption enhances adaptability and stability of filtering leaching procedure. The research results show that this technology can greatly improve the filtration properties of leaching solution and have reasonably Filtration speed to meet the production requirements and output iron-silicon slag can make secondary washing process. This technology has high production value to avoid loss of cobalt by entrainment of iron-silicon slag.