The method includes the following procedures: incubating the diluent of the peridium antigen. Adding a confining liquid and incubating. Mixing the processed specimen with the enzyme-marked antibody and incubating. Taking out the enzyme-marked board, adding the substrate fluid and incubating. Adding sulphuric acid solution to end the reaction. 450mm wavelength, determining the OD value and detecting the fipronil content in the specimen. The invention provides the features of easy of operation, the short detecting procedure. The invention can be utilized in the application and research area such as the environment control, the food industry and pesticide. It is particularly suitable for the grass root and the markets monitors section.