The invention discloses fluorescent wide chroma test paper for visually detecting copper ions as well as a preparation method and application of the test paper. The preparation method comprises the following steps: by taking a three-color ratio fluorescence probe as ink and taking filter paper as a solid-phase carrier through an inkjet printer, uniformly printing, thereby obtaining the test paper capable of visually detecting the copper ions, wherein the three-color ratio fluorescence probe refers to blue carbon dots, green quantum dots and red quantum dots, and the quantum dots are all modified by 3-mercaptopropionic acid. The three-color ratio fluorescence test paper is constructed to be used for visually detecting the copper ions by utilizing double-quenching principle first, the prepared detection test paper has the advantage that the color change range is wide compared with the conventional double-ratio fluorescence test paper, and along with addition of the detection object, test paper colors can be obviously identified by naked eyes from light scarlet, light flesh color, deep orange, grass green, dark olive green, slate blue, royalblue to cyanic color (Figure 4).