Abstract: The electromagnetic metamaterial absorber is a kind of electromagnetic energy harvesting device which sees rapid development and increasingly wider application. In this paper, the development status of the metamaterial absorbers at home and abroad is reviewed. Firstly, the principle of the energy absorption and the rectifier processing are described, respectively. Then the the methods and the techniques of the electromagnetic energy absorption and conversion are discussed with examples of some typical absorption and rectifier devices. Moreover, the features, the application scope, and the advantages & disadvantages of three kind of absorbers, namely, the multi-band absorbers, the broad-band absorbers, and the tunable absorbers are analyzed. Some methods for the improvement and the difficulties of the rectifier circuit are analyzed. In the end, the future development trend of the electromagnetic energy absorption and conversion is highlighted.