Carbon nanotubes (CNTs)possess excellent mechanical and electrical properties

but the random state of CNTs in their composite materials limits greatly to embody these performance .The approaches to align CNTs in composite materials processing were summarized in this paper .The main approaches including external force

electric field

magnetic field

liquid crystalline phase were introduced and the advantages and disadvantages of these approaches were evaluated .It can be concluded that the carefully designed force field

electric field

magnetic field and liquid crystalline phase enables CNTs to align in polymer composites processing

and thus improve the mechanical and electrical properties of polymer composites but the degree of alignment in all mentioned approaches has to be improved in the future .