Mycorrhiza is a symbiotic association formed between soil fungi and plant roots. Mycorrhizal fungi exchange soil-derived nutrients for carbohydrates from host plants, and therefore play an important role in the cycle of carbon and nitrogen in ecosystems. Research results indicated that mycorrhizal fungi can obtain ca. 4%?26% of total net primary production of host plants, and biomass and secretion (glomalin) of mycorrhizal fungi are important soil carbon-pool. Simultaneously, mycorrhizal fungi may decompose the complex soil organic compounds. Nitrogen is transported from extraradical to intraradical hyphae by a transferring procedure from inorganic to organic and inorganic nitrogen in mycorrhizae. Advances of recent mycorrhizal researches on the metabolic function and mechanism of carbon and nitrogen were summarized and related fields in future studies were also mentioned in this review paper.