A surface wettability determination system includes a sprayer, a light emission device and an optical detector. The sprayer is provided to spray a liquid on a detected surface of a detected object. The light emission device is provided to emit a light beam toward the detected surface. The light beam is reflected by the liquid on the detected surface to generate a reflected light. The optical detector is provided to receive the reflected light and output a determining signal, and the determining signal is related to a wettability of the detected surface.