The invention discloses an isolated ground radiation antenna and an MIMO antenna system. The isolated ground radiation antenna comprises a grounding plate which is laid on a printed circuit board, a clearance area which is an opening dug in the side edge of the grounding plate, an excitation structure which is arranged in the clearance area and used for feeding in a radio frequency signal and controlling impedance matching, a resonance structure which at least comprises a capacitor element and forms an annular resonance body together with the clearance area, and a decoupling structure which isarranged outside the clearance area and forms an annular decoupling body positioned outside the clearance area together with the capacitor element of the resonance structure. The current mode directions of the annular resonance body and the annular decoupling body are opposite. The annular resonance body and the annular decoupling body can be compatible with various types of antennas. Two antennas are arranged adjacently or connected to form a highly compact MIMO antenna system, and the MIMO antenna system has the advantages of compact structure, small unit size, short unit spacing, high isolation degree, low correlation and the like.