Abstract: In order to improve the third-order nonlinear optical property and the practical application of polyaniline-carbon natotube-doped polyvinyl alcohol composites were prepared by electrostatic interaction between carbon nanotubes and aniline via in situ polymerization.The third-order nonlinear properties of the samples were determined by the well-known z-scan technique at 532nm with 8ns duration,and the third-order optical nonlinear refractive indexes were calculated.Compared with pani,the third-order nonlinear properties of the samples could be improved obviously.They were prepared as film so that they could be used more widely.