The present invention discloses a multi-input multi-output antenna system comprising a first radiation unit, a second radiation unit, a radiation floor, a dielectric plate and a parasitic element. The first radiation unit, the second radiation unit and the parasitic element are printed on an upper surface of the dielectric plate, and the radiation floor is printed on a lower surface of the dielectric plate. The first radiation unit and the second radiation unit are planar monopole antennas, and the parasitic element is positioned between the first radiation unit and the second radiation unit. The system in accordance with the present invention can implement miniaturization of the antennas, and ensure two ports of an antenna have high isolation while maintaining good radiation performance.