Phage display antibody library has been proven to be a powerful technique used in development of ant ibodies. Since it was established in 1990, the technology has made enormous improvement and played more and more important role in basic research of biology, immunology, oncology, protein engineering, ligand-receptor studies and proteomics among others in last two decades while there is no report about the application of it in aquaculture so far. It is a success implication of phage display technique in antibody engineering in which antibodies or antibody f ragments are displayed on the surface of filamentous bacteriophage by genetic fusion to a coat protein of phage. Cooperating w ith the effective screening technique, aff inity panning, these form the principle of phage display ant ibody library. The most characteristic of it is a direct physical link between phenotype and genotype. So, the technology makes it practicable to improve characteristic of selected antibodies by genetic manipulation. In the present work, the background, principle and advantages of the powerful tool over traditional hybridroma technolgy are summarized. In addition, several key problems possible to face in the course of application of the technology, including improving the diversity of library , augmentation of library size, generation of high aff inity antibody and effective screening of specif ic antibody were dissertated. At last the possible implication prospect of phage display ant ibody technique in aquaculture was discussed, especially in elucidating the immune system of fish and producing large amount ant ibodies with important diagnost ic and therapeutic value in fish diseases.