The field experiments were conducted to study the effect of different water and nitrogen application on maize yield and soil residual available nitrogen through mulched drip irrigation. The main objective was to determine the suitable application amount of water and nitrogen to develop a preliminary theory for the harmonious target of high yield, high efficiency, low nitrogen residues and low loss of nitrogen. Results showed that the low irrigation (1 351 – 1 465 m³/hm²) cannot effectively increase the role of nitrogen fertilizer on the yield of maize. Combined application of 280 – 290 kg/hm² of nitrogen with irrigation of 1 400 – 1 800 m³/hm² led to the fastest increase in maize yield, but without synergistic effects of water with nitrogen on the yield. Combined irrigation of 1 800 – 2 100 m³/hm² with 250 – 280 kg/hm² of nitrogen obtained relatively higher yield and high synergistic effects of water with nitrogen on the yield. The residue of available nitrogen decreased from the shallow to the deep layer in the profile of 0 - 100 cm after harvest, and the quantity of water and nitrogen applied mainly affected the residue of available nitrogen in the layer of 40 - 100 cm. The residue of available nitrogen increased with the increasing nitrogen fertilizer. When the application rate was about 240 kg/hm², the quantity of residual available nitrogen increased slowly. The residue of available nitrogen increased rapidly when the fertilizer increased to above 240 kg/hm². The low irrigation (1 351 – 1 465 m³/hm²) decreased the conversion of fertilizer nitrogen to soil nitrogen and quantity of nitrogen residue. Enhancing the irrigation amount to 1 802 – 2 071 m3/hm2 promoted the conversion of nitrogen fertilizer to the soil nitrogen and increased the available nitrogen. When the irrigation reached about 2 197 – 2 315 m³/hm², the nitrogen migration with water in soil profile increased and reached to deep layer of > 1 m. The quantity of optimization of water and nitrogen coupling were in an approximate ellipse area. The irrigation of 2016 – 2100 m³/hm² with nitrogen of 228 – 250 kg/hm² in intersection area can be used as suitable amount for planting maize under mulched drip irrigation in the transition from Song-liao Plain to the Inner Mongolia Plateau.