Abstract: The aim of this study was to evaluate the effects of wheat/maize/soybean intercropping and nitrogen levels on maize growth and nitrogen (N) uptake. We conducted a double-factor randomized block experiment with two planting patterns (sole cropping and wheat/maize/soybean intercropping), with three N levels (0, 180, and 360 kg/ha) in 2013 and four N levels (0, 90, 180, and 270 kg/ha) in 2014. The overall aim was to determine the effect of N fertilizer and intercropping on maize yield, and then to further improve the wheat/maize/soybean intercropping system. The results showed that: 1) intercropped maize in the N₀ and N₉₀ treatments showed 20.5% and 7.5% lower yields, respectively, than that of sole-cropped maize (i.e., an intercropping disadvantage). In the N₁₈₀, N₂₇₀, and N₃₆₀ treatments, there was no significant difference in maize yield between the sole cropping and intercropping planting patterns. As the nitrogen supply increased, the dry matter content in maize first increased and then decreased. The maximum dry matter accumulation rate in maize was at the spinning to harvest stage. Compared with sole-cropping, intercropping significantly and negatively affected the stem growth of maize in all N treatments. The maize stem growth rate was 12.5% lower in the intercrop than in the sole crop at the jointing stage, but this effect was mitigated when the amount of N fertilizer applied was 180 kg/ha or greater. The maize biomass and N accumulation in maize were significantly lower in the intercropping system than in the sole cropping system, and N transformation from nutritional organs to the seeds was also lower in the N₀ and N₉₀ treatments than in the sole cropping system. In the N₁₈₀, N₂₇₀, and N₃₆₀ treatments, the maize biomass and N accumulation in maize did not differ significantly between the two cropping systems, while the N transformation rate was higher in the intercropping system than in the sole cropping system. The highest N optimum transport index was in the N₁₈₀ and N₂₇₀ treatments, indicating that these treatments were most favorable for N-transporter function. In conclusion, it is important to provide the right amount of N to provide stability to the wheat/maize/soybean relay-planting system. Optimizing the amount of N supplied can increase maize yield, improve the efficiency of N absorption and transport, and reduce the effects of the growth and N absorption of maize on wheat. Under the conditions of this study, the amount of N fertilizer required for intercropped maize was 180 kg/ha.