The growing population is driving global demand for increased agricultural production while arable land is being lost with urbanization and degradation. Intercropping is often a reliable way of using land and other resources more effectively. Maize-soybean intercropping may raise land productivity by improving the use efficiency of water, nutrient, and radiation resources. Water and fertilizer conditions have obvious influences on canopy growth and development, thus affect radiation capture and utilization. However, few experiments were carried out to investigate effects of different water and nutrients combinations on radiation capture, competition and utilization in intercropping system. Therefore, an experiment was carried out to investigate effects of different water and nitrogen levels on radiation interception, competition and utilization in a maize-soybean strip intercropping system. The intercropping system consisted of two rows of maize and three rows of soybean flanked each other. The experiment design was consisted of 2 water levels, as sufficient water supply (soil moisture low limit was set as 75% of the field capacity) and water deficit (soil moisture low limit was set as 60% of the field capacity), and 2 nitrogen levels, as nitrogen application of 7.5 kg N per 667 m² and no nitrogen application. The total number of treatments was 4 and 3 replications were arranged. Experimental results indicated that under same nitrogen application level, the fraction of radiation intercepted by the intercropped crops on sufficient water supply plots was higher than those on water deficit plots during the medium-late stage. Under same water level, the fraction of radiation interception of the intercropped soybean on nitrogen application plots was slightly greater than that on no nitrogen application plots, but the difference was not significant. However, the radiation interception fraction of the intercropped maize on nitrogen application plots was significantly greater than that on the no nitrogen plots. For the treatments with same nitrogen application, the radiation competition ratio of the intercropped maize increased and the radiation competition ratio of the intercropped soybean decreased as the water supply was improved during the period of 64 days after sowing to maturity. Under same water application level, the radiation competition ratio of the intercropped maize on nitrogen application plots was significantly greater than that on no nitrogen plots during the period of 73 days after sowing to maturity, while it was not significant that the difference between the radiation competition ratios of the intercropped soybean on the two nitrogen treatments. For sufficient water supply treatments, light use efficiency (LUE) of the intercropped maize was 3.87 g/MJ on nitrogen application plots, and slightly higher than that (3.81 g/MJ) on no nitrogen application plots. However, for water deficit treatments, LUE of the intercropped maize was 3.86 g/MJ on nitrogen application plots and 3.72 g/MJ on no nitrogen application plots, an increasing of 3.6%. Under sufficient water supply, LUE of the intercropped soybean on nitrogen application plots (1.62 g/MJ) was higher than that on no nitrogen application plots (1.57 g/MJ) by 3.2%, while, a LUE of 1.55 g/MJ for the intercropped soybean on nitrogen application plots was nearly same to a LUE of 1.54 g/MJ on no nitrogen application plots under water deficit. It can be deduced that the influence of water condition on LUE of intercropped soybean was more significant than that of nitrogen condition.