This paper aims to reveal the mechanism of droplet movement on the surface with gradient surface energy.The microscopic contour of the gradient energy surface，which was fabricated on a base of silicon chip by diffusion-controlled silanization of alkyltrichlorosilanes，was measured with atomic force microscope.It was found that there existed numerous silane groups with hydrophobic behavior on the fabricated surface whose distribution density increased with the increase of the distance from the diffusion source of silane This is the main reason for the formation of gradient surface energy.By using visual experiments，the mechanism of droplet movement on the gradient energy surface was investigated based on the analysis of the system free energy transform of the droplet.With the high speed imaging system，the effect of liquid film lubrication on droplet movement was studied visually.The experimental results showed that the energy consumption of droplet movement was compensated by the release of the system free energy caused by the gas-solid interface replaced by the liquid-solid interface of the droplet when it was moving towards the hydrophilic side of the gradient energy surface.Liquid film lubrication was favorable to the droplet movement on the gradient energy suface.