A phage display single chain fragment variable library constructed on pⅢ protein of M13filamentous phage was screened using B-lymphocyte stimulator and FP248 as selective molecules. After four rounds of panning, there was a remarkable enrichment in the titer of bound phages. Twenty phage clones were selected from the last round and screened by means of phage-ELISA. With the antibody phages as primary antibodies in Weste blot, we developed a method for detecting the specific antigen. The dilutions of antibody phages depend on the affinity between antibody-displayed phage particles and antigens.