The invention relates to the technical field of communication, in particular to an antenna system and a mobile terminal. The antenna system comprises a metal shell, system ground, a mainboard and an antenna unit, wherein the system ground is connected with the metal shell, the mainboard is provided with mainboard ground, a main path and a matching network, the mainboard ground is connected with the system ground, the matching network comprises a first matching component and a second matching component, the main path comprises a first radio frequency source, a first antenna port, a second antenna port and a second radio frequency source, the matching network is at least arranged between two arbitrary adjacent parts of a first radio frequency source, a first antenna port, the second antenna port and the second radio frequency source, and the antenna unit is connected with the mainboard via the first antenna port and/or the second antenna port so that the antenna unit is coupled to a top framework or a bottom framework to form a first antenna, a second antenna and a third antenna. By the antenna system, the manufacturing cost can be reduced to the great extent, the mainboard is not needed to be replaced during debugging, and the antenna system is convenient to debug.