The field emission (FE) properties of single-walled carbon nanotubes (SWNTs) are of great importance, especially in applications involving flat panel display devices such as field emission displays (FED). The electron emitters of the FED must be long-lived and stable, and possess a low turn-on threshold voltage and a high current density at a given external field. In general, the emission source should have highly oriented and well-distributed tubes in order to utilize the characteristics of the nanotubes for FE. A notable method using plasma for the synthesis of the aligned CNTs was developed by Ren et al. We report the modified field emitter of CdS quantum-dot deposited on SWNTs (DcS/SWNTs). As a II-VI semiconductor compound, CdS has attracted considerable interest in optoelectronic application because of its relatively low electron affinity, high chemical inertness and sputter resistance.