The invention relates to an anti-gonyautoxin GTX2,3 monoclonal antibody immuno-colloidal gold labeled test strip and its preparation method, and belongs to the field of rapid detection technology of saxitoxin. By the application of GTX2,3 artificial antigen prepared by a new method, GTX2,3 monoclonal antibody is obtained. According to the test strip, a bottom layer is a support layer, an intermediate layer is an adsorption layer, and a protective layer is fixed on the adsorption layer. Starting from a test end, the adsorption layer successively comprises an adsorptive fiber layer, a nitrocellulose membrane layer and a water absorbing material layer at the tail end. Gold-labelled antibody in the gold-labeled antibody fiber layer is anti-GTX monoclonal antibody. A gonyautoxin control line and a detection line are arranged on the nitrocellulose membrane layer. The preparation method comprises the following steps: coating of antigen GTX2,3-Gly-KLH, preparation of the monoclonal antibody of gonyautoxin GTX2,3, preparation of colloidal gold, colloidal gold labeled antibody, preparation of the test strip and the like. The test strip is prepared by the use of the monoclonal antibody obtained by the new GTX2.3 artificial antigen preparation method. The test strip has advantages of fast, accurate and simple detection, high sensitivity and field testing.