1. An object analyzation method of an optical touch system, comprising: capturing a first image across a touch surface of a panel with an image sensing apparatus, wherein the first image has an object image formed therein corresponding to the position of a pointer on the touch surface; defining an image window corresponding to the object image in the first image; and determining whether the pointer is touching the touch surface or hovering over the touch surface according to the brightness difference between a first pixel group and a second pixel group defined in the image window; wherein the first pixel group comprises at least a high brightness pixel while the second pixel group comprises at least a low brightness pixel, and the pixel value of the high brightness pixel is larger than a preset threshold while the pixel value of the low brightness pixel is smaller than the preset threshold.