This study presents the design of a high-isolation ultra-wideband (UWB) four-element multiple input multiple output (MIMO) antenna with a single notched band.The dimensions for this antenna are 65 mm×65 mm×0.8 mm.The four slot antenna units are placed horizontally and orthogonally, and the antenna is fed by a coplanar waveguide, facilitating ease of manufacture and integration.The defect ground and cross isolation branches are used for decoupling.Furthermore, a U-shaped slot is etched on the antenna radiation patch to create a notched band at 4.35-6.08 GHz, which effectively suppresses WLAN communication interference (5.15-5.825 GHz).The measured operating band of the proposed antenna is 2.46-10.6 GHz, with an isolation level of less than -20 dB.The notched band is generated at 4.35-6.08 GHz, which effectively suppresses the WLAN interference.Additionally, the envelope correlation coefficient is maintained below 0.02, and the diversity gain exceeds 9.998.The measured performance is robust, demonstrating significant potential for extensive application in UWB-MIMO communication systems.