The invention discloses a two-dimensional liquid-phase colorimetric instrument-free quantitative analysis method. The method simultaneously utilizes the reaction that diastatic enzyme catalyzes and hydrolyzes starch molecules with lower water solubility to generate products with good water solubility, such as glucose, and a simple mechanism that color detection reagents with excellent water solubility and water dispersibility can diffuse in different distances in reaction solutions with different water solubility; the diffusing lengths of the color detection reagents in the reaction solutions increase along with the increase of diastatic enzyme activity concentration, so that by visually observing and measuring the diffusing lengths, two-dimensional liquid-phase colorimetric instrument-free quantitative analysis of a target analyte can be realized. The method provided by the invention has a simple detection process, experiments can be developed by a person without professional skill training, quantitative signal reading can be performed without using any instrument equipment, so that the analysis cost is reduced, and the method has broad application prospect.