Abstract: To obtain the anti - LPS of E.coli polyclonal antibody, 5 weeks old rabbits were immunized with lipopolysaccharid of E.coli, The polyclonal antiserum was purified by caprylic acid- ammonium sulfate precipitation and sephadex gel chromatography, then their purity and yield were measured respectively with SDS-PAGE and ultraviolet spectrophotometry, The titer and cross reaction of antibody was assayed with ELISA; Yield and ELISA titer of puritied rabbit polyclonal antiserum against LPS of E.coli were 6.95 mg/ml and 1:12800; Rabbit polyclonal antiserum against LPS of E.coli was obtained, and can be used in laboratory detection kit.