Abstract: Salmonella typhimurium is the most common pathogenic bacterium in salmonella and had flagellin of antigenicity which could induce immune system to produce antibody. Our research adopted direct extract method to get flagellin of salmonella, and used this protein as antigen to immune mice for flagellin polyclonal antibody. In this research, valence and specificity of antibody were tested through indirect ELISA testing. SDSPAGE experiment showed protein stripe was single and molecular weight was 57 ku, which means extracted flagellin was the target protein and it's of high purity. ELISA testing indicated that the valence of antibody was1 ∶ 102400 and it had cross reaction with Salmonella choleraesuis only while it didn ' t react with other 6salmonella and 6 common pathogenic bacteria of non-salmonella. It stated this antibody had high valence and good specificity and could be used to couple with magnetic bead.