Recently, the Multiple-input multiple-output (MIMO) antennas have been used a lot and attracted many researchers in advanced high-speed wireless communication systems. MIMO antennas are an essential part not only in access points but also in end-user devices. This technology allows a significant increase in channel capacity, but also lead to a challenge of minimize mutual coupling and in the meantime reserved antennas’ compact size. In this study, we propose a triple-band MIMO antenna design. By using a symmetric parasitic structure, isolation between radiation elements is significantly improved. Besides, each antenna element is designed using a combination of planar structure and 8 Fibonacci curves that makes it compact in size and easy to fabricate in the circuit board of 5G/ Wi-Fi 6 terminals. With a total dimension of 34.8*68.2*1.6mm3, the proposed MIMO antenna design can operate at three bands of 2.4GHz, 3.5GHz, and 5GHz with wide bandwidths of 11.4%, 9.4%, and 14.58%, respectively. The results are analyzed based on simulation, measurement, and experiment