Abstract: The present disclosure relates to the technical field of tests, and in particular, to a thin test strip, a test strip roll, and an application of the thin test strip. The thin test strip includes: a waterproof top layer, a composite layer, and a waterproof bottom layer in sequence from top to bottom, where the composite layer includes a sample collection pad, a colloidal gold conjugate pad, a color developing membrane, and a sample absorption pad, the waterproof top layer does not cover the sample collection pad and completely covers the colloidal gold conjugate pad, the color developing membrane, and the sample absorption pad, and the composite layer is I-shaped. The waterproof top layer and the waterproof bottom layer are made from polyethylene terephthalate (PET) waterproof transparent membranes.