Designed　a　millimeter-wave　MIMO　antenna　array　with　high　gain　and　high　isolation　for　5G　mobile　terminal　broadband.　The　antenna　system　consists　of　four　linearly　arranged　array　elements　and　a　3×5　metasurface　structure.　The　introduction　of　the　metasurface　structure　improves　the　isolation　of　the　antenna.　The　resonant　frequency　of　the　proposed　antenna　system　is　40GHz.　In　the　entire　operating　frequency　band　38.7-41GHz,　the　isolation　of　the　array　is　greater　than　29dB.　The　peak　gain　of　the　array　antenna　is　14.5dB.　The　antenna　structure　is　compact　and　the　overall　size　is　10mm×22mm×0.508mm.　At　the　same　time,　the　diversity　performance　of　the　antenna　array　is　also　very　excellent,　adapting　to　the　design　needs　of　5G　terminal　antennas.　©　2024　IEEE.