Nanocomposites of single-walled carbon nanotubes modified polypyrrole (PPy/SWNTs) were synthesized successfully by in situ oxidative polymerization method in the FeCl3·6H2O solution. The morphological structure, electrical conductivity and thermal stability of the nanocomposites were characterized by TEM, SEM, FTIR and TGA. The PPy/SWNTs were 50-100 nm in diameter of PPy coating uniformly on the surface of the SWNTs. FTIR spectra revealed the presence of covalently interaction between the PPy and the carbon nanotubes. The electrical conductivity of PPy/SWNTs composite and pure PPy were 93 and 8.0×10-3 S/cm, respectively. Meanwhile, the PPy/SWNTs composites possessed higher thermal stability (65.9 wt. % weight loss at 600 °C) compared to pure PPy (81.2 wt. % weight loss at 600 °C), the content of SWNTs was 15.3 wt. %.