In this study, we investigate how nanodroplets diffuse on smooth surfaces through molecular dynamics (MD) simulations and theoretical analyses.Molecular dynamics simulations show that nanodroplet surface diffusion is different from that of single molecules and solid particles.The dependence of nanodroplet diffusion coefficient on temperature undergoes a transition from linear to nonlinear as the surface wettability is weakened due to the coupling of temperature and surface energy.We also develop a simple relation for the diffusion coefficient by using the contact angle and contact radius of the droplet.It works well for a wide range of surface wettabilities and different sized nanodroplets, as confirmed by MD simulations.