Intercropping is one of the most important and sustaibale cropping practice in agro-ecosystems. The study was conducted under field conditions in the arid Horqine sandy land in Baicheng District, Jilin Province, Northern China in 2011. A randomized complete block design with four replications was used. Treatments comprised different mono cropping and intercropping patterns, TO: sole cropping of oat, TOS-O: oat in the intercropping of oat and soybean, TOG-O: oat in the intercropping of oat and groundnut, TS: sole cropping of soybean, TOS-S: soybean in intercropping of oat and soybean, TG: sole cropping of groundnut, TOG-G: groundnut in the intercropping of oat and groundnut. In intercropping patterns, oat in oat-groundnut had obtained the highest dry matter in all stages. The highest value of protein percentage and organic matter in heading stage, grain filling stage, and grain dough stage was achieved in groundnut in oatgroundnut intercropping. The maximum value of protein percentage and organic matter in booting stage and ripening stage was related to soybean in oat-soybean intercropping. The results of this study clearly indicate that intercropping oat and groundnut affects the growth rate of the individual species in mixtures as well as the dry matter yield and nitrogen accumulation. The highest seed yield was obtained for mono-cropping of soybean, followed by mono-cropping of groundnut and oat. Oat seed yield intercropping of oat and groundnut, and intercropping of oat and soybean were 1208.00 kg/ha, and 832.3 kg/ha, respectively. The highest grain yield was obtained when soybean was grown together with oat, where the higher yield of intercrop is due to the better usage of nutrient, water and light. LER in all intercropping patterns were higher than 1. LER in intercropping of soybean and oat, and intercropping of groundnut and oat were 1.41, and 1.30, respectively. With these LER values, 29.07% and 23.07% of land were, respectively, saved in intercropping of soybean and oat, and intercropping of groundnut and oat, respectively, which could be used for other agricultural purposes. In both intercropping of soybean and oat, and intercropping of groundnut and oat, CI were less than 1, which means that both these two intercropping patterns have positive effects.