Psychrophilic microorganisms have successfully colonized all permanently cold environments from the deep sea to mountain and polar region. The evolved features, genotypic and/or phenotypic of the organisms make them surmount the negative effects of low temperatures and enable growth in these extreme environments. The mechanism of cold adaptation might cover fields of cold-adapted enzyme, maintenance of membrane fluidity, role of cold shock protein, cryoprotectant and antifreeze protein. The cold-adapted microbes and its products were utilized in a broad range of industrial, agricultural and medical processes based on the achievement of mechanism research.