In the head-disk interface (HDI) of a hard disk drive (HDD), the effects of lubricant deformation on the flying characteristics of a head slider increase as the flying height decreases. Therefore, it is very important to investigate the deformation and flow characteristics of lubricant on a recording disk. In particular, in heat-assisted magnetic recording (HAMR), laser heating of the lubricant induces surface tension distribution and evaporation of lubricant, which may cause deformation of the lubricant film. In this paper, flow characteristics of liquid nano-film of perfluoropolyether (PFPE) film on solid substrate is investigated experimentally. Using the modified Boltzmann-Matano method, diffusion coefficients of liquid nano-step are calculated. In addition, thicknesses of mobile layer and bonded layer of PFPE are measured.