Abstract: Mineral nitrogen losses in dryland involve ammonia volatilization,nitrate leaching and denitrification.The objective of this paper is to investigate the relationship between soil mineral losses and soil moisture as well as mineral nitrogen content under water-saving irrigation conditions.The field experiments were carried out in a field with winter wheat and corn for three years.Based on the observations of field experiments and the analysis of relationship among initial soil mineral nitrogen content,irrigation amount,fertilizer supply,and mineral nitrogen losses,a conceptual model is developed to estimate soil mineral nitrogen losses and evaluate the impact of irrigation water and fertilizer N input on the environment.The results show that crop grain yield increased with the increased nitrogen losses.Nitrogen use efficiency is also limited by soil water content under water-saving irrigation conditions.