Poly(ethylene-co-isosorbideterephthalate)(PEIT)/multi-walled carbon nanotube (MWCNT)/ethylene terpolymer composites were prepared by a melt mixing process. The effects of MWCNT and the ethylene terpolymer of nanocomposites on the mechanical, thermal and electrical properties were investigated. MWCNT and ethylene terpolymer from 1 to 5 phr and 5 wt.% and 10 wt.% were added to the PEIT matrix, respectively. The thermal properties were evaluated by DSC and TGA. The morphology, mechanical properties and electrical characteristics were assessed by FE-SEM, a notched Izod impact strength tester and a surface resistance meter. As a result, we found that the PEIT/MWCNT/ethylene terpolymer composites have higher conductivity and better mechanical properties than neat PEIT resin.