Crustacean, especially crabs and shrimp have become more and more important objects in world aquaculture. Hemocyanins(Hcs) are the very important chromoprotein accounting for more than 90% of all the crustacean hemolymph protein. In recent years, many investigations have been focused on Hcs. In this paper, the research advances in crustacean hemocyanins were summarized following aspects: the basic structure, property of oxygen transport, immunity, anabolism of Hcs and so on. Hcs occurs as hexamers composed of six heterogeneous monomeric subunits. Each subunit holds an active site of two coppers, which corresponds to only one oxygen molecule. Resently, researchers put forward that Hcs hold important immune functions in crustacean. Hcs maybe exert their defence functions at least by two ways:one way is Hcs’s converting to phenoloxidase by cleavage of N-terminal sequences of Hcs; the other way is releasing antimicrobial fractions by cleavage of C-terminal of Hcs, which are broadly antimicrobial against a variety of bacteria and viruses. A newly-study proved that Hcs posess the property of agglutinin with low activity, which also contributes to immunity in crustacean to a certain extent. Hcs can also serve as carriers of metal ions, storage of protein. Besides Hcs can be used as a sign to observe the distribution of some molecules connecting with them. Hcs are synthesized in F-cell cytoplasm of the hepatopancreas. Evidence proved that ambient factors could also lead to Hcs’ anabolism.