The invention provides an image sensor package and method for fabricating the same. The image sensor package comprises a first substrate comprising a sensor device thereon and a hole therein. A bonding pad comprising a first opening is formed on an upper surface of the first substrate. A second substrate comprising a spacer element with a second opening therein is disposed on the first substrate. A conductive plug is formed in the hole and passes through the first and second openings to the second substrate to electrically contact with the bonding pad. A conductive layer is formed on a lower surface of the first substrate and electrically connects to the conductive plug. A solder ball is formed on the conductive layer and electrically connects to the bonding pad by the conductive plug. The image sensor package further comprises a second substrate bonding to the first substrate. The image sensor package is relatively less thick, thus, the dimensions thereof are relatively reduced.