The optical properties of carbon nanotubes are studied. Align carbon nanotubes films were synthesized by chemical vapour deposition method in our lab. The diameter of carbon nanotube is about 20-30 nm. The amorphous carbon impurities in align carbon nanotubes film were removed by a series of deal with processes. Carbon nanotubes were examined up by using scanning electron microscope, transmission electron microscope and Raman spectrum.The reflected spectrum, transmission spectrum and absorption were measured. Results show that carbon nanotubes have strong absorption from visible region to mid-infrared (IR) region. Photoluminescence spectra of carbon naotubes film were studied at 488, 632.8, and 1060 nm excited laser wavelength. Results show sthat there are nonlinear processes in luminescence of carbon nanotubes under ultrafast laser excitation (1064 nm, 60 ps) conditions. A broad photoluminescence peak was location at 1.6 eV (about 768 nm), this phenomenon was considered to relate to van Hove singularities, and was a three-photon-absorption process.