Abstract: The Cu-Ni alloy cast irons of different chemical constitution were designed,and the corrosion rate in room-temperature concentrated alkaline solution was measured by the static hydrometer method,the microscopics and phase composition of alloy cast iron were observed by optical microscope and XRD.The results show that with copper content increased,the small flake graphites’ refinement around Cu-Ni alloy cast iron become noteable,the primary graphite is refined firstly,and then is coased,meanwhile the quantity of it increased.When copper content exceeds the certain value,free copper element is precipitated in Cu-Ni alloy cast iron,and these new phase become active cathode phase,thus reduce the corrosion resistances of alloy cast irons.Under the room-temperature concentrated alkaline solution static condition,the corrosion resistance of alloy cast iron with 4.5wt% Cu is better.