The study of ore-forming fluid is one of the major and frontier subjects in the field of mineral deposits and geochemistry. Among which, the mixing of different kinds of fluid is an important way to cause the deposition of ore metal. Based on the latest research fruits from home and abroad, this paper synthetically introduces the recent progress related to this topic, which includes the present flocculation of metals during the mixing of river water and sea water, as well as several main processes of fluid mixing during different kinds of ore formation, especially the mixing of magmatic water and meteoic water. The principal mechanisms of metal deposition from fluid mixing i. e. cooling, dilution, pH change, and redox reaction, have also been discussed in this paper.