The basic theory of the wetting surface is first introduced, and recent research on droplet directional transport is then reviewed. The driving forces of droplet directional transport mainly originates from biomimetic topology or external-field. In the part of biomimetic self-driven research, droplet directional transport inspired by natural structures such as spider silk, Nepenthes alata and pine needles is summarized based on the Laplace pressure gradient or surface energy gradient, and the corresponding directional transport mechanisms are analyzed and the theoretical formulas of driving force are derived. In the part of external-field induced research, the external-field mainly includes magnetic field, light field, electric field, heating field and surface vibration. Note that the force induced by the magnetic field can act inside the droplet, outside the droplet, and the droplet surface. The light field mainly includes near-infrared light, ultraviolet light and visible light. The electric field mainly includes electrostatic attraction, electrostatic repulsion and indirect action. The heating field is mainly induced by steam, surface-deformation and thermo-capillarity. Surface vibration mainly includes horizontal vibration, vertical vibration and surface acoustic wave. Based on different droplet transport mechanisms, the directional transport characteristics of five fields are further analyzed and compared. Finally, the problems and future directions for droplet directional transport on wetting surface are summarized and prospected.