The invention provides an optical fingerprint sensor including: an image sensing layer having an array composed of a plurality of sensing blocks; a collimating layer disposed on the image sensing layer and having a plurality of through holes penetrating from the top surface to the bottom surface of the collimating layer; a light guiding layer disposed in the collimating layer, and a glass cover layer disposed on the light guiding layer, the top surface of the glass cover layer receiving a finger touch, wherein the image resolution of the optical fingerprint sensor is defined by the number of sensing blocks, and there are a plurality of through holes directly above each of the sensing blocks.