According to the requirements of communication quality and transmission rate, a compact UWB MIMO antenna with high isolation is proposed for wireless communication system. The proposed antenna can achieve an ultra-wide band from 3.3 GHz to above 12 GHz and the isolation higher than 22.5 dB in the whole frequency range. The size of antenna element is 50 percent reduced by cutting out half of the original antenna element and the frequency band is basically unchanged. The antenna is composed of two mirror symmetrical antenna elements. An isolation strip is added between two elements to improve the isolation and a 6dB improvement of the isolation is achieved. The proposed antenna system has good radiation performance at each observation frequency points. The maximum realized gain is about 4.32dBi and the radiation efficiency is ranged from 83% to 92% at the passbands. All the results show that the proposed antenna system can be a good candidate for UWB MIMO communication applications.