Abstract: Wheat and maize inter-cropping is the main cropping pattern in the irrigated area of Hexi corridor, Gansu Province, which plays an important role in improving the local grain yield. Besides the optimum use of light and heat resources, adequate supply of nutrients and water per unit area are the other key factors ensuring high output for inter-cropping. Due to less water in Hexi region, melt-snow from Qilian Mountainhas has been mainly used for irrigation proposes.Therefore, the increasing crop water use efficiency is an important approach to efficient utilization of water resources. The influences of the different rates of nitrogen applied on water use and yield were studied in wheat and maize inter-cropping by field experiment in Hexi arid irrigated area. The results showed that compared to different nitrogen treatments, the soil water content in wheat belt changed little with the increase of nitrogen rates applied while maize belt's soil water content was decreased. With the increase of nitrogen application, both wheat and maize yields increased first and then decreased. The yields of wheat and maize inter-cropping reached the highest when nitrogen fertilizer was applied to 375 kg·hm^-2; on the contrary, the yield decreased when nitrogen fertilizer was 562.5 kg·hm^-2. Nitrogen rates had a significant effect on the water use efficiency of wheat and maize. The water use efficiency increased with the increase of nitrogen application with a single peak, over 375 kg·hm^-2 nitrogen application, the water use efficiency was decreased.