Abstract: A field experiment was conducted to investigate the effect of different root partition patterns on wheat/maize competitiveness under intercropping system and how it affects yield. Two root partition patterns (plastic film and nylon mesh partition patterns) were used. The study shows that wheat/maize competitiveness in intercropping system steadily increases from sowing to flowering stage of wheat, and then decreases. Competitive advantage of wheat over maize under intercropping decreases by root partitioning. Intercropping system without root partition increases competitive advantage of wheat by 20.5% and 4.9% respectively, compared to those with plastic film and nylon mesh partition. Land equivalent ratios (LER) of intercropping systems without root partition, with plastic film partition and nylon mesh partition are 1.46, 1.20 and 1.39 respectively. Yield for intercropping system is quadratically correlated with wheat competitiveness to maize. Improving wheat/maize competitiveness in intercropping systems could increase yield. The stage of wheat flowering is critical for optimizing wheat competitiveness.