Abstract: Methanotrophs can oxidize methane, playing an important role in regulating methane emission, and gaining increasing attention by the researchers around the world. Two biological pathways are involved in methane oxidation, i.e., anaerobic oxidation and aerobic oxidation, which are governed by anaerobic and aerobic methanotrophs, respectively. In this paper, the research advances about methanotrophs were summarized, with the focus on the phylogeny and taxonomy of methanotrophs, the key enzymes responsible for the aerobic oxidation of methane, the microorganisms involved in the anaerobic oxidation of methane, and the mechanisms of microbial methane consumption. The application prospects of the two methane oxidizers in greenhouse gases removal, pollutants degradation, biological denitrification, and recovery of metals and sulfur compounds were also analyzed.