In this paper, a high-isolation broadband MIMO antenna is designed, which consists of two symmetrical radiation units, and two symmetrically open hexagonal resonant rings are printed on the front of the substrate, and small hexagons are placed in the ring to achieve a wide frequency band. To improve the isolation between the antenna ports, a stepped slot is introduced on the ground plate on the back of the substrate and a resonant branch is inserted to reduce coupling within the operating band. The simulation results show that the working frequency band range of the antenna is 6.39GHz~7.71GHz, The relative bandwidth is around 19%.the isolation between the two ports of the antenna reaches more than 17dB in the entire wide band, and the maximum gain of the antenna in the broadband is 5.1dBi, which has good radiation performance .