We present a simple, effective, and accurate method to grow single-walled carbon nanotube (SWNT) multilayer thin films with layer-by-layer (LbL) nano self-assembly. The thin film is assembled on the substrate by alternate adsorption of SWNTs and poly(dimethyldiallylammonium chloride) (PDDA). Scanning electron microscope (SEM) inspection shows that the SWNT multilayer is formed with a dense network of nanotube bundles. The average thickness of a single (PDDA/SWNT) bi-layer is measured as 76 Å. The volume and mass ratios of SWNTs in the multilayer are calculated as 63.2% and 75%, respectively. With nanoindentation measurement, the Young's modulus of the SWNT thin film is approximately 17 GPa. The electro-thermal properties of the SWNT multilayer are studied with current-voltage (I-V), four-point probe, and rapid thermal annealing (RTA) techniques. The conductance of the SWNT thin film at 300°C is measured as 2.29 mS, which is 50 times higher than that at room temperature (0.045 mS).