NiFe 2 O 4 powders as microwave catalyst were prepared by chemical precipitation method, and characterized by XRD technologies. Their catalytic activities towards the degradation of brilliant green (BG) solutions were investigated under microwave irradiation (MW). The effects of pH, addition amount of catalysts on the degradation efficiency of BG were studied. Moreover, the degradation mechanism of BG was also analyzed. And the degradation process was investigated by UV–vis, FT-IR, TOC, HPLC and Ion chromatogram techniques. The experimental results indicated that the degradation percentage of BG could reach up to 97%, corresponding to 91% of TOC removal, and BG was degraded into inorganic ions such as NO 2 − , NO 3 − under microwave irradiation time 2.0min. It indicates that NiFe 2 O 4 could act as an efficient catalyst in the microwave degradation process, and there exist synergistic effects of MW and NiFe 2 O 4 on the degradation of BG. With the advantages of low cost and rapid processing, this novel MW/NiFe 2 O 4 composite could gain a promising application in treatment of various dyestuff wastewaters on a large scale.