Switching of wettability is achieved in situ, which is a challenge of materials science. Generally, changing liquid droplet is required to ex situ study the wettability response before and after the surface given a treatment, in the sense that the liquid impregnation in the surface structures is irreversible. Herein, an in situ wettability switch is achieved by utilizing the same liquid droplet to characterize the dynamic wettability when the conducting polymer is being stimulated. The oil droplet is facilitated to escape from the nanoscale traps through electrochemically tuning surface composition and surface micro/nanostructures, permitting a reversible and rapid transition between partly wetting and superantiwetting state. This in situ switch is promising for integration into a microfluidic system for the control of the liquid droplet's motion.