Abstract: The difference between intercropped fababean and wheat in using differ ent nitrogen source has been studied by pot experiment with root barrier and 15N trace technique. The results showed that wheat growth was enhanced without root barrier, leading to higher biomass and N acquisition than those with both solid barrier and mesh barrier. However, the growth of faba bean was unexpectedly sup pressed due to wheat competition and the short growing periods made the recovery not possible. Thus, the biomass and N acquisition of faba bean without root bar rier was lowest in the three root barrier patterns. 15N% abundance was highest i n wheat with mesh barrier, and 15N% abundance was lowest in faba bean without ba rrier, which suggested that the competition of wheat for fertilizer N was strong er, and the competition leads to high percentage of N fixation from atmospheric N2.