An optical touch-control system is provided. The optical touch-control system includes: a display unit; a light source; a retro-reflective touch-control device; at least two image capturing units, and a processor. The image capturing units are configured to capture a plurality of images in front of the display unit, which are generated by the retro-reflective touch-control device reflecting the light emitted from the light source. The processor determines whether at least one first cluster is in the images from the image capturing units based on a first threshold. The processor further calculates a touch position of the retro-reflective touch-control device on the display unit based on the at least one first cluster.