The invention discloses a method of distinguishing multiple touch points applied to an optical touch system which includes a panel for indicating a first touch point and a second touch point thereon and a camera unit for capturing an image relative to the first touch point and the second touch point. The image has a first dark area and a second dark area corresponding to the first touch point and the second touch point respectively. In the method, if it is observed that the first dark area and the second dark area merge into a first single dark area and a second single dark area at current time and previous time respectively, the respective positions of the first dark area and the second dark area are determined and the respective coordinates of the first touch point and the second touch point are also determined.