A three-piece compact optical lens system includes, in order from the object side to the image side: a flat panel assembly, a first lens element; a stop; a second lens element; and a third lens element. Wherein a distance from an object to an image plane along the optical axis is OTL, a distance from an image-side surface of the flat panel to the image plane along the optical axis is PTL, an image height of the image plane is Y, an object height of a chief ray of the image height of the image plane which corresponds to the image-side surface of the flat panel is P, and they satisfy the relations: 2.5 mm