The effects of full plastic-film mulching with bunch planting on soil nitrogen mineralization and inorganic nitrogen in semi-arid region were studied to provide the theoretical basis for optimizing field nitrogen fertilizer management. The field experiment was conducted in the semi-arid region of middle Gansu province from 2014 to 2017，the involved three treatments were full plastic-film mulching with bunch planting(MS)，traditional plastic-film mulching and bunch planting(M)，no mulching bunch planting(CK)，and the soil nitrogen mineralization，inorganic nitrogen content in growth period of spring wheat were studied. The results showed that MS treatment increased soil water content of 0 ～ 20 cm layer，accelerated soil nitrogen mineralization rate of 0 ～ 15 cm layer，and significantly increased net mineralization of NO^3--N and mineral nitrogen，compared with M，MS treatment increased by 29.02% and 27.81%，respectively，which increased content of inorganic nitrogen in 0 ～ 20 cm layer，mainly NO^3--N，but reduced the content of soil NO^3--N and mineral nitrogen in 40 ～ 200 cm，with the content of NH4+-N not change significantly. According to the analysis for the wheat growth stage，the mineral nitrogen was net fixed in T2 ～ T4(14 ～ 62 d)stage，was net mineralized in the T5 ～ T7(63 ～ 116 d)stage，and was net mineralized in the whole growth stage. The net mineralization of mineral nitrogen in the MS，M and CK treatment was 23.9，18.7 and 8.5 mg/kg，respectively. In the middle stage T5(63 ～ 75 d)of wheat growth，the net mineralization rate of soil nitrogen of MS treatment[1.61 mg/(kg·d)]reached the maximum，compared with M[ 1.39 mg/(kg·d)]and CK[0.27 mg/(kg·d)]，which was significantly increased by 15.83% and 496.30% respectively. Compared with M，the yield and water use efficiency of MS increased by 8.81% ～ 59.45% and 5.91% ～ 22.15%，respectively. Therefore，full plastic-film mulching with bunch planting improved the soil hydrothermal conditions and accelerated the mineralization rate of soil nitrogen，which increased the availability of soil nitrogen and improved the soil nitrogen supply capacity，and significantly improved yield and water use efficiency of spring wheat in semi-arid region.