Protein is always the focus of research for global scientists for it is the most important molecule in living forms. Immunoprecipitation is a classical method to researching interaction different proteins on the basis of specificity between antibody and antigen and it is also regarded as an effective way to recognize the mutual physiological action between two kinds of proteins in cells. It presents that the immune complexes produce protein precipitation in some certain condition after the specific binding between soluble antigen and antibody in liquid or gel. Immunoprecipitation, agglutination, neutralization reaction and the reaction between antigen and antibody are called classical immunological techniques. With the deepening of the protein research, more complicated methods are produced on the basis of combination of immunoprecipitation and other methods. Thus methods of protein analysis become more various and its application area become wider. This technology has a wide application in gene, protein, and their reaction.