The invention relates to a small high-isolation double-notch UWB (Ultra-wide Bandwidth) MIMO (Multiple Input Multiple Output) antenna, which comprises a main floor board, a first floor board limb, a second floor board limb, a first metal strap, a second metal strap, a third metal strap, a first antenna unit, a second antenna unit, a first tail end opening gap and a second tail end opening gap, wherein the third metal strap is used for connecting the two floor board limbs. Due to the application of the two floor board limbs, a first excitation port and a second excitation port can be placed on the upper edge of a basal board, so that the impedance bandwidth of the antenna units can be effectively improved, and the isolation between the two antenna units is also effectively increased. The technical problem that the current UWB MIMO antenna cannot simultaneously realize small size, small cross coupling and wide bandwidth is solved. The first metal strap and the first antenna unit form a first annular loop, the second metal strap and the second antenna unit form a second annular loop, so that the high frequency notch is realized. Due to the application of the first tail end opening gap and the second tail end opening gap, the low frequency notch is realized. Therefore, the double-notch function is realized.