Biomass chemical looping gasification (CLG) is a promising approach for the utilization of biomass energy. The oxygen carrier plays an important role in the CLG process, and its performance is the key factor affecting the CLG process. In this paper, the performance evaluation indexes, the types of oxygen carriers, preparation methods and their effects on tar yield in CLG technology were reviewed. Through analysis and comparison of current research results, it was pointed out that Fe carrier is the most widely used in the process of biomass CLG, and Ni carrier has higher activity, larger oxygen carrying capacity, and higher catalytic conversion efficiency for tar. Therefore, Ni carrier shows better application prospects. In the future, the key direction in this field is the development of highly active and environmental-friendly oxygen carriers, thus promoting the industrial application of CLG process. © 2020, Chemical Industry Press Co., Ltd. All right reserved.