The present study is conducted to determine effects of elevated atmospheric CO2 concentration on soil soluble C、available P and K, and organic P in rhizosphere and non-rhizosphere after crops harvested under two N levels with FACE(free air carbon dioxide enrichment) systems. The results showed that compared with ambient CO2, elevated CO2 did not decrease soil available P and K but increase them with increased biomass of rice and wheat and soil available P and K were increased more in wheat season than in rice one, more in root rhizosphere than in non-rhizosphere. Soil soluble C was increased by elevated CO2 and more carbon input to soil under NN treatment resulted in a more decrease of soil organic P at LN than at NN, in rhizosphere than in non-rhizosphere of rice. The decrease of organic P played an important role in the increase of soil available P. More N application, for example, NN treatment was beneficial to increase of soil organic P and then perform a positive function in keeping the soil P available, which could insure the continuously response of crops to elevated CO2.