Organisms living on earth are markedly affected by the geomagnetic field (GMF). In this review article, it was firstly introduced of the magnetic fields (MF) and GMF, and then the magnetic response phenomenon of organisms to MF and/or GMF was furtherly reviewed in details. It has been verified that many species of organisms, ranging from migratory birds to anaerobic bacterium etc., have some physiological and behavioral responses to the GMF, that is, resulting of changes in growth, development and reproduction or providing information to guide their migration or diffusion of some migratory animals by using the GMF playing a role as a 'map' or a 'compass'. To date, there are three generally recognized magnetic-response mechanisms (or hypotheses) of organisms, i.e., the magnetic-response mechanism based on iron minerals and depended light and radical pairs hypothesis. Moreover, the magnetic-response mechanism based upon the bio-compass of magnetic proteins (including CRY and MagR) reported by our Chinese scientists has aroused widespread concern, while it hasnt been verified through experiments in vivo. At present, the change in GMF intensity is becoming more and more serious under the background of global change, while it is just beginning to study the magnetic response of organisms worldwidly (especially in China), the relevant research should be carried out in depth in order to providing scientific evidences based on bio-magnetic responses for the dealing with the changes in GMF.