Abstract: Based on carbon nanotubes (CNTs) film prepared by floating catalyst chemical vapor deposition (CVD) method, the component of amorphous substance coating on CNTs surface was firstly analyzed by infrared spectroscopy. Moreover, heat-treatment and acid-treatment were used separately to investigate the effects of amorphous substance and residual Fe catalyst in CNTs film on tensile orientation behavior of CNTs film. The results indicate that the amorphous substances on surface of CNTs in CNTs film prepared by CVD method are oligomer containing oxygen, alkane or olefin groups, which can be removed through 350℃ treatment in air. The component of CNTs film can significantly impact the aligning and rearranging behavior of CNTs film. The oligomer on surface of CNTs film tends to enhance the interaction between CNTs and Fe catalyst particle serves as crossing junctions of the CNTs network, which both improve the CNTs orientation degree and the size of bundles, and hence increase the tensile stability and breakage toughness of the CNTs film. After stretching, the CNTs film has better wettability with epoxy solution, and the tensile strength and modulus of CNTs film/epoxy composites reach 1 228 MPa and 94.5 GPa respectively, which are increased by 337% and 729% than the initial random CNTs film/epoxy composites.