The invention discloses an indirect competitive ELISA kit and a detection method for detecting the content of mercury in textiles based on a mercury monoclonal antibody, belonging to the technical field of heavy metal detection. According to the invention, immunoreaction is carried out on a mouse based on Hg-ITCBE (isothiocyano-benzyl-ethylenediamine tetra-acetic acid)-KLH (keyhole limpet hemocyanin) as an immunizing antigen to obtain a monoclonal antibody for detecting mercury; and an indirect competitive ELISA method based on the monoclonal antibody is suitable for rapid, accurate and high-throughput measurement of mercury extracted from the textiles by virtue of simulating acidic sweat, achieves a biological assay method for mercury in the textiles, constructs a kit, provides a technical support for safe detection of light textiles for children, and has the advantages of high efficiency, intense affinity, high detection sensitivity, simple and convenient operation and the like.