The invention discloses a method for visually detecting melamine through nanogold hydrosol without an aptamer. The method comprises the following steps: adding plants into absolute ethyl alcohol, boiling, carrying out extraction, and filtering, so as to obtain filtrate; adding activated carbon into the filtrate for decolorization, and standing for 1 day, so as to obtain a faint yellow plant extracting solution; diluting the faint yellow plant extracting solution, and refrigerating a obtained diluent for later use; and extracting the diluent, adding a to-be-tested sample into the diluent, uniformly mixing, adding a chloroauric acid water solution to adjust the pH, reacting, and detecting melamine by virtue of a visual colorimetric method or an ultraviolet visible spectrophotometry. The method is rapid, simple, convenient, high in sensitivity and strong in anti-jamming capability, and the detection limit to melamine can reach 15nM. The method can be used for visually detecting a melaminesample, the field sampling detection can be realized, the detection sensitivity is high, and the qualitative and quantitative detection of melamine can be realized; and the sample can be detected ina severe environment, so that the application range of the sample is wide.