CdS nanospheres doped with graphene for ethanol detection were fabricated via a simple hydrothermal process. Various methods including XRD, SEM, HRTEM and XPS were carried out to characterize the structure and morphology of the as-prepared CdS nanospheres. Moreover, the ethanol sensing performance of the CdS/G sensor was studied in detail. The results indicated the CdS/G sensor demonstrated high response, ultra-fast responding and recovering ability towards ethanol than pristine CdS. The excellent ethanol sensing properties of the CdS/G sensor were result from the enhanced surface reaction assisted by graphene. Compared with other sensors published by previous researchers, our CdS/G sensor still exhibited great potential.