Abstract: An experiment was carried out with treatments different in atmospheric CO2 concentration level (370, 550, 700 μmol/mol) and nitrogen supply [0, 5, 10 g N/(m2?a)] on the OTC (Open Top Chamber) equipment for study the effect of nitrogen deposition and elevated atmospheric CO2 concentration to the content of the soil total phosphorus and available phosphorus element which were contain in the Deyeuxia angustifolia community in Sanjiang Plain. The results indicated that: elevated atmospheric CO2 concentration combined with nitrogen deposition consecutive run two growing season, there was no noticeable changing about the content of soil total phosphorus and available phosphorus on the same treatment; each treatment only affect soil phosphorus content in 0-10 cm layers had significant effect on soil phosphorus content below 2 layers. Along with the increasing of the CO2 concentration, the content of soil total phosphorus and available phosphorus in 0-10 cm layers appeared the tendency, as first increasing and then decreasing. The nitrogen added no significant effect on the soil total phosphorus content, but reduced available phosphorus content in the 0-10 cm layers. Soil total phosphorus content was closely related with soil depth, and decreased with the increase of soil depth.