ABSTRACT In this article a series of Epoxy/polythiophene nanocomposite were prepared by solution mixing method and their mechanical and thermal properties were investigated as a function of polythiophene content. For this propose polythiophene nanoparticles were prepared using chemical oxidative polymerization of thiophene monomer and served as nanofiller. FTIR analysis demonstrated that polythiophene synthesized successfully. Mechanical properties analysis demonstrated that yielding strength and initial modulus of nanocomposite are highly improved with the increment of PTh content compared to pure epoxy resin. Thermal analysis using TGA test reveal that addition of PTh into the epoxy resin increased thermal stability of epoxy based nanocomposite. Keywords: Nanocomposite, Epoxy resin, Polythiophene (PTh), Mechanical Properties