The invention discloses a double-antibody sandwich method for detecting salmonella typhimurium in food based on monoclonal antibodies, belonging to the technical field of immunoassay. Salmonella typhimurium ATCC13311 and smooth salmonella typhimurium LPS are adopted for mixed immunity of a 7-week BALB / c mouse, 10 LPS monoclonal antibodies are obtained by immunity, fusion and screening, horse radish peroxidases (HRP) are labeled respectively, and the salmonella typhimurium is paired two by two. A sandwich enzyme-linked immuno sorbent assay (ELISA) method is established by taking 6E2 CGMCC No.7206 monoclonal antibodies as coated antibodies and enzyme-labeled antibodies and by taking the salmonella typhimurium as standards, and the LOD is 500cfu / mL. The sandwich method, established by using the monoclonal antibodies which are highly uniform in physicochemical property and high in specificity and can be prepared on a large scale, is high in sensitivity and low in cost; the salmonella typhimurium is not in cross reaction with salmonella enteritidis, salmonella arizonae, E.coli, E.coliO157:H7, enterobacter sakazakii, staphylococcus aureus and listeria monocytogenes; a quick and efficient analysis way is provided for detection of the salmonella typhimurium in the food.