The invention discloses an immunocolloidal gold detection card for pretilachlor and a preparation method thereof, belonging to the technical field of detection of residues of veterinary drugs in animal-originated food. A test strip in the shell of the detection card is composed of a PVC rubber sheet, a sample pad, a colloidal gold binding pad, a coating film and a water-absorbing pad, wherein a colloidal gold film is a glass cellulose film containing a monoclonal antibody against pretilachlor, the coating film is a cellulose nitrate film which is provided with a line T and a line C, the line T is coated with pretilachlor protein conjugate, and the line C is coated with a goat anti-mouse IgG antibody. The immunocolloidal gold detection card is effectively used for rapid detection of pretilachlor, is convenient and fast and produces accurate results.