Superlong carbon nanotubes (CNTs), which have perfect structures, extraordinary electrical, thermal and mechanical properties, have shown great potential for applications in nano/micro devices and superstrong fibers.Compared with agglomerated CNTs and vertically aligned CNTs, superlong CNTs usually have low areal densities and narrow growth windows.Small catalyst nanoparticles tend to merge into bigger ones during the high temperature chemical vapor deposition (CVD) process, which accordingly promote the growth of short and multi-walled CNTs.Here we introduced silica nanospheres to anchor catalyst nanoparticles and effectively improved the areal density of ultralong CNTs.