The present disclosure provides an antenna-in-package system and a mobile terminal. The mobile terminal includes a main board, wherein the antenna-in-package system includes a substrate, a metal antenna provided on a side of the substrate facing away from the main board, an integrated circuit chip provided on a side of the substrate facing towards the main board, a feeding network provided in the substrate and spaced apart from the metal antenna, and a circuit connecting the feeding network with the integrated circuit chip. The circuit is electrically connected to the main board. The feeding network is provided with a slit at a position corresponding to the metal antenna. The metal antenna is fed with power by coupling with the feeding network via the slit.