The invention designs and synthesizes a sliver ion fluorescence sensor molecule-1H-imidazole[4,5-b] phenazine derivative, wherein phenazine in the sensor molecule is a stable system with a rigid structure; the sensor molecule is used as a fluorophore, so that the solution of the main body molecule emits strong fluorescence; imidazole and a furan ring are used as an identifying functional site; and in a water-containing medium, the molecule identifies sliver ions with high selectivity, and the identifying process is not distributed by other positive ions. Besides, when the silver ions are added at the room temperature, the fluorescence intensity of the solution is quickly weakened within 30 seconds, so that a very good naked-eye identifying effect can be achieved. Ag<+> response test paper manufactured by utilizing the sensor molecule also can conveniently and quickly detect the silver irons in an environmental system.