A novel sensor was assembled by combining CdTe quantum dots (QDs) with nitrogen-doped graphene( NG) on the surface of glassy carbon electrode. The sensor as-assembled with the NG/CdTe QDs composite exhibited high electrochemiluminescence (ECL) intensity and long-time ECL stability. The ECL mechanism and effect factors on ECL emission of the sensor are discussed. Significantly, the sensor was used in ascorbic acid (AA) detection based on the ECL quenching of AA. The results show that the sensor has a linear response range from 0.04 to 200 mu M and the detection limit of 0.015 mu M for AA. (C) 2014 Elsevier B.V. All rights reserved.