Abstract: The amide carbon nanotubes (Amid-CNT)/polyacrylonitrile (PAN) composite solution was synthesized by solution polymerization. The Amid-CNT/PAN composite fibers were prepared by wet spinning methods. The effects of Amid-CNT on the structure of PAN fiber were characterized by Fourier transform infrared spectrum, Raman spectrum, different scanning calorimetry, thermogravimetric analysis and scanning electron microscopy. The results show that the Amid-CNT and PAN macromolecules form the strong interfacial interactions. The Amid-CNTs in the Amid-CNT/PAN composite fibers are highly orientated in the processing of the formation, which increase the orientation of nitrile groups in the fiber from 1.61 to 2.30. The initiation temperature of the exothermic reaction for the composite fibers shifts from 212.30℃ to 206.01℃ in the air atmosphere compared with the PAN fiber, and the total evolve heat decreases from 3054 J/g to 2346 J/g. The initiation temperature of loss weight for the Amid---CNT/PAN composite fibers decreases by 3.7℃ compared with PAN fiber, and the residual mass for the composite fibers improves by 13.5% compared with PAN fiber at 700℃. The structures from SEM images show that the Amid---CNT/PAN composite fibers have more fibrillations than the PAN fiber.