A method for packaging an image sensor includes the steps of: providing a substrate having an upper surface and a lower surface; mounting a frame layer to the upper surface of the substrate to form a chamber together with the substrate; mounting a photosensitive chip to the upper surface of the substrate and within the chamber, and electrically connecting the photosensitive chip to the substrate; mounting a transparent layer to the frame layer with a B-stage adhesive applied therebetween; pre-baking the B-stage adhesive to slightly adhere the transparent layer to the frame layer; testing the image sensor to determine whether the image sensor is passed or failed; and post-baking the passed image sensor to completely cure the B-stage adhesive so that the transparent layer is firmly adhered to the frame layer.