The fabrication and characterization of single-walled carbon nanotube (SWNT) multilayers, micropatterns and interconnections on plastic substrates are reported in this paper. The SWNT-based multilayers and devices are fabricated with a simple, fast, inexpensive, low-temperature, and highly efficient technique combining layer-by-layer (LbL) nano self-assembly, microlithography, and lift-off techniques. The SWNT multilayers are alternating layers of SWNTs and poly (dimethyldiallylammonium chloride) (PDDA). Lithography and lift-off techniques are used to pattern the SWNT multilayers. SWNT microstructures with linewidth of 5 μm are fabricated and characterized. The thickness of a (PDDA/SWNT) bi-layer is approximately 76 A. Two-terminal SWNT thin film based interconnections are fabricated on flexible substrates. Current-voltage (I-V) characterization and four-point probe measurement show that the resistance of the interconnection is nonlinearly inversely proportional to the number of the assembled SWNT layers. The nano-assembled polymer/SWNT composite can be used in many applications due to its low cost, light weight, and long lifetime.