Provided is an antenna system, including a system ground unit, a metal back cover, a frame as antenna radiator, and a grounding circuit, a feeding circuit and a tuning switch, the antenna radiator includes a main radiator and an auxiliary radiator; the main radiator includes a first main radiator which forms, together with the metal back cover, a first main gap, a second main radiator extending from the first main radiator and forms, together with the metal back cover, a second main gap, and a first fracture separating the first main radiator into two parts; the auxiliary radiator includes a first auxiliary radiator which forms, together with the metal back cover, a first auxiliary gap, a second auxiliary radiator extending from the first auxiliary radiator and forms, together with the metal back cover, a second auxiliary gap, and a second fracture separating the first auxiliary radiator into two parts.