The invention discloses a P-rGO-C60 nanocomposite material and a P-rGO-C60-Pt@Au nanocomposite material, and also discloses an electrochemical DNA aptamer sensor for SDM detection, wherein the electrochemical DNA aptamer sensor is prepared by the following method: 1) treating an SDM aptamer by using a TCEP solution for standby application; 2) polishing a glassy carbon electrode into a mirror surface, processing the electrode, and drying for standby application; 3) electrochemically cleaning the electrode, swashing with water, and drying; 4) dropwise adding 6-10 [mu]L of P-rGO-C60 solution intothe surface of the glassy carbon electrode, drying, dropwise adding a GOD solution to the electrode; 5) dropwise adding the P-rGO-C60-Pt@Au solution to the electrode surface, and drying at room temperature; 6) taking an SDM binding aptamer, dropwise adding on the electrode, and incubating at room temperature; and 7) immersing the electrode in the GOD solution, and thus obtaining the product. A method for detecting the SDM by using the sensor is also disclosed.