An intercrop partially meets the nitrogen requirement of the companion crop due to the transfer of the symbiotically fixed nitrogen from the legume to the non-leguminous crop. The economic benefits of sugarcane in the intercropping treatments with low-nitrogen application treatments were 3.17 to 26.34% higher than those of the high-nitrogen application treatments. The efficiency of soybean nitrogen fixation and amount of nitrogen fixation in the monoculture treatment were significantly higher than for the sugarcane–soybean intercrops. Sugarcane depletes soil nutrients considerably, but legume intercropping patterns increase productivity per unit of land and enable crops to more effectively utilize nutrients and improve soil fertility and field conditions. Sugarcane juice purity is an important index in estimating sugarcane quality and is one of the key factors in predicting sugar yield. Sugarcane–soybean intercropping with reduced nitrogen application is feasible in practice when considering the lowered costs and sustained sugarcane yield.