Quantum dots (QDs) and graphene oxide (GO) are extremely attractive and important nanomaterials in analytical applications because of their their unusual chemical, physical and electronic properties. In this work, CdTe QDs with the size of about 3 nm were prepared and a novel electrochemical sensing material of ascorbic acid on GO/CdTe QDs/GC electrode was explored. Transmission electron microscopy (TEM) was used to examine the morphological characterization of CdTe QDs and cyclic voltammetry (CV) and electrochemical impedance spectroscopy were used to perform the electrochemical investigations of the GO/CdTe QDs/GC electrode. Because of the synergy between the CdTe QDs and GO, this novel sensing based on CdTe QDs/GO/GC electrode responded even more sensitively and selectively than that based on bare GC electrode. Effects of pH value, buffer concentration, deposition potential and deposition time and electroactive interferents on the response of GO/CdTe QDs/GC electrode for ascorbic acid sensor were discussed. Under optimum working conditions, a linear response of the modified electrode was obtained over the concentration range of 32.3–500.0 µM with the detection limit of 6.1 µM for ascorbic acid. Finally, the inexpensive, reliable and sensitive modified electrode based on GO/CdTe QDs/GC was succesfully applied for the determination of ascorbic acid in citrus samples.