A portable optical touch system is disclosed in the present invention. The portable optical touch system includes two camera devices movably connected with each other and respectively disposed on two corners of a plane. Each camera device includes an imaging module for capturing an image of an object on the screen, an adjusting module connected to the imaging module for determining whether the two imaging modules are positioned on the same plane, and a measuring module connected to the imaging module for calculating a distance between the two imaging modules. The portable optical touch system further includes a controlling unit electrically connected to the camera device for calculating a coordinates of the object on the plane by analyzing the distance between the imaging modules and the images captured by the imaging modules.