Abstract: In order to meet the demand for multi-channel, space compactness and miniaturization in the field of communication, a dual-band UWB-MIMO antenna loaded with a Y-shaped branch and square slit structure is proposed. The initial antenna structure is based on the circular patch, and in order to improve the performance of the antenna, an octagonal structure is excised internally by rotating an elliptical patch, and the feeding mode is microstrip line feeding. By etching a square groove on the floor, the distribution path of the current on the surface of the antenna is effectively changed, and a new resonance mode is excited to realize the dual-frequency characteristics of the antenna and greatly expand the antenna bandwidth. At the same time, a Y-shaped branch is loaded on the floor, which introduces a new coupling path to cancel with the original coupling path, and improves the isolation between the antennas. Finally, the Y-shaped branch and the square groove are co-optimized to achieve the best performance of the designed antenna. The test and research results demonstrate that when S₁₁ parameter of the antenna≤−10 dB, the working frequency band is 5.8 GHz~14.8 GHz, the relative bandwidth is 87%, the isolation of the antenna drops from −10 dB to below −24 dB and as low as −36 dB, the ECC is about 0.01, the gain is 2.9 dBi~4.9 dBi, the radiation efficiency reaches 95%, and the measured results are not much different from the simulation results, which is reliable. The results show that the antenna realizes miniaturization, high isolation and ultra-wideband with excellent diversity performance, which can expand the communication capability, guarantee the stable and efficient operation of the system, and has strong application potential in multiple scenarios such as wireless communication.