In order to enhance the compatibility between multi-walled carbon nanotubes (CNTs) and polylactic acid (PLA), the surfaces of CNTs were first pre-treated using acid solution (HNO3) to modify the CNTs surface with carboxylic groups (-COOH).Subsequently, the stearyl alcohol was grafted onto carboxylic groups with the assistance of dehydrating agent, N,N-dicyclohexyl-carbodiimide (DCC), then the chemically modified CNTs (CNT-C18) was obtained.