In recent years, polymer – based nanocomposites have found wide applications in various industries. Polypropylene / ethylene – propylene - diene monomer /Nanoclay (PP/EPDM/Nanoclay) nanocomposite is one of these materials that has many applications in automotive and aircraft industries. Welding as a fabrication process has attracted the attention of researchers for joining these materials. Among welding processes, laser welding because of its advantages can be a choice for joining of PP/EPDM/Nanoclay nanocomposites. In this paper, the effect of CO2 laser power, scan velocity, stand-off distance and clay content on impact strength of butt-welded PP/EPDM/Nanoclay 3.2 mm sheets is investigated. The response surface methodology (RSM) is used to develop a statistical model relating the above parameters to the impact strength of the weld joint. The results indicated that increase in clay content and scan velocity decreased the impact strength whereas stand-off distance increased it. The maximum impact strength of 70 J/m is achieved at laser power of about 103 W, velocity of 400 mm.min-1, stand-off-distance 8 mm and clay content of about 1.3% wt.