Abstract: Mycorrhizal fungi are an important member of soil microorganisms, not only rich in genetic diversity and species diversity,  but also in functional diversity, which mainly manifest in: 1) affecting the origin, evolution, and distribution of terrestrial plants, 2) promoting plant growth and development, 3) enhancing plant tolerance against environmental stress, 4) remedying polluted and degraded soils, 5) promoting agricultural, forestry, and animal husbandry production, and 6) maintaining ecological equilibrium and stabilizing ecosystem and its sustainable productivity. With the development of technique and research, more functions contributed by mycorrhizal fungi would be discovered.

Key words: mycorrhizal fungi, function, plant evolution, remediation, ecosystem, agricultural and forest production