The present invention relates to a folding mechanism of an exercise treadmill having a treadmill frame and a support frame. A connecting rod is mounted on the support frame and extends to the front lower side of the exercise treadmill such that the other end of the connecting rod is pivotally connected the front portion of the treadmill frame. In addition, a ground touching roller is mounted to either side of the front end of the bottom of the treadmill frame. When the rear end of the treadmill frame is lifted to perform a folding action, the ground touching rollers are operative to facilitate the lifting action of an operator such that the operation is easy and has a labor-saving effect.