The research status and prospects on the coevolution of lichens are reviewed in this paper. The origin of lichens dated back to the Precambrian. During the endless evolutionary process, some unique features have been induced because of symbiotic interactions, for example, the mutualistic anatomic structure, synthesis of unusual secondary compounds, inconsistent degree of DNA methylation within the lichens. Some lichenologists found that there were great differences in morphology, physiology and heredity between cultivated and symbiotic fungus and algae by cultivation experiments. The high specificity between symbionts due to coevolution was also found by artificial resynthesis.