An efficient method for nitrogen dioxide (NO2) gas detection in single-walled carbon nanotubes (SWCNTs) ordered using dielectrophoretical (DEP) technology after dispersion in sodium dodecyl sulfate (SDS) surfactant solution. Atom force microscopy (AFM) and scanning electron microscopy (SEM) images revealed that SWCNTs were assembled between the microelectrodes. SWCNTs were affected by the electrophoretic force which was carried out by the related theoretical analysis in a nonuniform electric field. SWCNT field effect transistors (SWCNT-FETs) geometry was obtained. The electrical performance of NO2 gas sensor with SWCNT-FETs structure was tested before and after NO2 at room temperature. Experimental results that the efficient assembly of SWCNTs were obtained when the applied alternating current voltage has a frequency of 2 MHz and an amplitude of 10 V. SWCNTs-based gas sensor had high sensitivity to NO2, and the electrical conductance of NO2 gas sensor reduced two times. SWCNTs surface gas molecules were washed out by means of ultraviolet ray irradiation in 10 minutes. NO2 gas sensor could be duplicated. Meanwhile, it also provided an effective method of assembly and manufacture for other one-dimensional nanomaterials assembly of nanoelectronic devices.