In the present paper, ore-forming geofluids in crust were classified into five fluid systems:(1)ore-forming fluid-system in connection with acid-intermediate magmatic activity in continental crust;(2)ore-forming fluid-system in connection with submarine basic magmatic activity;(3)basin fluid system in connection with sedimentary basin evolution;(4)metamorphic fluid system in connection with regional metamorphism; (5)mantle fluid system produced by mantle. The occurrence, evolution, main features, and ore-forming processes of each fluid systems were briefly discussed.