Abstract: Carbon nanotubes (CNTs) possess atomically smooth inner surface and nanoscale pores, which lead to extremely high permeability and selectivity as nanofiltration membranes. In this review, preparation methods, permeation properties, merits and limitations of several typical membranes based on CNTs are introduced, such as buckypaper membranes, random distributed CNT/polymer composite membranes, and vertically-aligned CNT/polymer composite membranes. It is suggested that nanofiltration membranes based on vertically-aligned CNTs may be promising since they could make a full use of the characteristics of CNTs.