With root partition method and ¹⁵N-isotope dilution method, field and pot experiments were conducted to examine the research included the effects of intercropping of rice cultivated aerobic soil and ground nut on dry matter production, quantity of nitrogen uptake, biological nitrogen fixation, and nitrogen transfer from groundnut to rice at three nitrogen level, namely 0, N 225 kg hm^-2, N 300 kg hm^-2. Soil nitro gen fertility was also investigated under the new cultivation system. The results show that 1) there was a yield advantage in the new intercropping system compared to monocrop rice. The dry matter, for example, of rice in intercropping at three nitrogen application rates were 30.03%, 10.1%, 2.2% higher than those in monocropping, respectively, and the same situation happened for the nitrogen uptake. 2) Biolog ical nitrogen fixation estimated by ¹⁵N-isotope dilution method in groundnut decreased with the increase nitrogen level while intercropping can improve biological nitrogen fixation of groundnut. 3) N-transfer from groundnut to rice was evident but no co-relation between biological nitrogen fixation and nitrogen transfer was found in this experiment. 4) Intercropping system could increase significantly the mineral nitrogen during the whole growth stage, thus improving soil nitrogen fertility.