Objective： To obtain the completely humanized Fab antibody against idiotypic antibody from a phage-display library of schistosoma japonicum. Methods： A schistosoma japonicum library of phage-display human Fab library was constructed using genes from spleens of 3 patients with schistosoma japonicum infection. Soluble egg antigen（SEA） and soluble worm antigen preparations （SWAP） were used to screen schistosoma japonicum immune mouse serum IgG. The positive recombinant phages identified by ELISA were used to infect E.coli TOP10 for the production of soluble Fab antibodies. Results： A schistosoma japonicum human Fab phage-display library consisting of 4.3 × 106 clones was successfully constructed. The sequencing results demonstrated that it was a human Fab gene library. After five rounds of panning， sixty randomly selected clones from the enriched phage library were tested with ELISA， and four clones（A3，B6，C4，C17） were found to bind to IMS （Ab1） but not to SEA and SWAP. The clone B6 was expressed and identified by SDS-PAGE. Sequencing was also carried out. Conclusion：A schistosoma japonicum human Fab phage-display library could be successfully constructed， from which anti-idiotypic antibody （B6） of schistosoma japonicum is obtained. And it is useful for further study on anti-idiotypic antibody vaccine development of schistosoma japonicum.