The present disclosure provides a method for making carbon nanotube slurry. The method includes the following steps. First, a carbon nanotube array is provided on a substrate, the carbon nanotube array comprises a number of carbon nanotubes. Second, the carbon nanotube array is trimmed by a laser to obtain a trimmed carbon nanotube array comprising a plurality of trimmed carbon nanotubes having uniform lengths. Third, the trimmed carbon nanotube array is removed from the substrate to obtain the trimmed carbon nanotubes. Fourth, the trimmed carbon nanotubes are mixed with an inorganic binder and an organic carrier to obtain the carbon nanotube slurry.