An integrated circuit package in package system includes: a base integrated circuit package with a base lead substantially coplanar with a base die paddle and having a portion with a substantially planar base surface; an extended-lead integrated circuit package with an extended lead having a portion with a substantially planar lead-end surface; a package-stacking layer over the base integrated circuit package; and the extended-lead integrated circuit package over the base integrated circuit package including: an end portion of the extended lead, directly on the package-stacking layer, and the extended lead exposed by and extending away from the bottom of the side of an extended-lead encapsulation and bending downwards toward the direction of the package stacking layer with the substantially planar lead-end surface coplanar with the substantially planar base surface.