The invention discloses a method for quantitatively detecting the activity of 8-OhdG (8-hydroxy-2'-deoxyguanosine) based on an aniline deposited electrochemical sensing electrode. The method comprises the following steps of preparing a DNA (Deoxyribonucleic Acid) tetrahedral structure with sulfhydryl; modifying, on a gold electrode, the DNA tetrahedral structure with the sulfhydryl to obtain an electrode of which the top end is connected with an 8-OhdG aptamer and which has the DNA tetrahedral structure with the sulfhydryl; forming a G-quadplex electrode; forming a polyaniline deposited electrochemical sensing electrode; detecting a generated current signal of polyaniline by utilizing an electrochemical method, so as to detect the activity of the 8-OhdG. By using the method for quantitatively detecting the activity of the 8-OhdG based on the aniline deposited electrochemical sensing electrode, the detection sensitivity on the 8-OhdG is greatly improved. In compassion with a conventional electrochemical detection method using a reduction peak of the 8-OhdG as a signal, the detection limit is decreased by two orders of magnitude. By using the method for quantitatively detecting the activity of the 8-OhdG based on the aniline deposited electrochemical sensing electrode, the preparation of a complicated material and a DNA labeling probe is not needed; the defects that the preparation of the material and the DNA labeling probe causes that the detection cost is high, the operation is fussy and the reproducibility is poor can be avoided. The method for quantitatively detecting the activity of the 8-OhdG based on the aniline deposited electrochemical sensing electrode has the advantages of being low in cost, being quick, simple and convenient, and being high in sensitivity.