The invention discloses a metamaterial-based 5G communication miniaturized broadband MIMO antenna and belongs to the technical field of antennas. The unit antenna of the present invention comprises afirst dielectric substrate, an antenna radiator, a first coplanar waveguide feed structure and a second coplanar waveguide feed structure. Four antenna units constitute a four-unit MIMO antenna. Adjacent antenna units have a rotation angle of 90 degrees and an interval therebetween. A metamaterial-based broadband decoupling structure is loaded onto a plane vertical to the antenna in the interval space. The MIMO antenna of the present invention has the advantages of an extremely wide operating frequency band, a very small size, an extremely low decoupling structure profile, and high isolation degree.