Effect of elevated atmospheric CO₂ on arbuscular mycorrhizal diversity in paddy-wheat field was investigated. Results showed that no significant effect was found on AM fungal colonization, but in the treatment of normal N application rate, it decreased the total number of AM fungal total species, and however, had no significant effect on the average number of species in every soil sample. In treatments of higher N application rate, the effect on number of species was insignificant. Higher N fertilization decreased AM fungal diversity both in treatments of normal and elevated atmospheric CO₂.