The invention discloses a simple and low-cost silver ion visual quantitative detection method. The method adopts an organic solvent which can be mutually soluble with water and has density more than 1g/mL at the temperature of 25 DEG C for dissolving 3,3',5'5'-tetramethyl benzidine (TMB). When aqueous solution containing silver ions is dropwise added into TMB solution, Ag<+> quickly oxidizes TMB to generate blue quinoid benzidine. As the adopted organic solvent can be taken as a bicolour layering intelligent regulator, a unique bicolour mixed solution which is blue at the upper layer and colourless at the lower layer is obtained finally; meanwhile, the length of the blue solution is positively correlated with concentration of Ag<+>, so that quantitative detection on Ag<+> at micromole level can be realized by visualizing and observing with naked eyes and measuring the length of the blue solution. According to the method disclosed by the invention, a Ag<+> detection process is extremely simple, an operator not trained professionally can carry out an experiment, more importantly, a quantitative signal can be read without using instrument or equipment, and on-site analysis and real-time detection on a sample can be realized while analysis cost is greatly reduced.