Abstract: CNTs/PLA composites were prepared by solution blending method in the presence of pristine carbon nanotubes(MWCNTs)and carboxylated carbon nanotubes(MWCNTCOOH). The dispersity of CNTs, crystallization morphology, electric conductivity and degradation were studied. The results show that MWCNTCOOH are dispersed more homogeneously in PLA than the pristine MWCNTs by SEM. POM(Polarizing Optical Microscope) results shows that the MWCNTs act as effective nucleating agents and decrease the crystal size. With the addition of a little MWCNTCOOH, the volume resistivity of the nanocomposite decreases by 7 orders of magnitude, and the degradation also increases by MWCNTCOOH.