The invention discloses an auxiliary method for detecting whether genetically modified protein exists in food. The method comprises steps as follows: total protein is extracted; the total protein is injected to sample adding holes of a detection device, holes in a first perforated plate are closed, the detection device comprises the first perforated plate, a sample adding device and a hollow fiber polypropylene film tube, the sample adding device comprises a second perforated plate, a cone and multiple sample adding channels, the hollow fiber polypropylene film tube is arranged between the first perforated plate and the second perforated plate, and a first antibody specifically bound with to-be-detected genetically modified protein is attached to the inner wall; the holes in the first perforated plate are opened, and washing is performed; the holes in the first perforated plate are closed again, and a second antibody is injected into the sample adding holes in the detection device; the holes in the first perforated plate are opened again, and washing is performed; whether a mark of the second antibody exists in a hollow fiber polypropylene film is detected, and if the mark exists, the genetically modified protein exists in the total protein and existence of a genetically modified ingredient in the raw material is determined.