Abstract: By using soil bores and closed chamber methods, field experiments were carried out in the semiarid area of dry land to study the effects of irrigation and rainfall on the N2O loses. Meanwhile intact soil cores C2H2 incubation test was performed in the lab to study influences of wet and dry alternated on the N2O emission so that further to explain the field results. The results showed that N2O emission in the dry land usually is low but it will increase rapidly after irrigated or rainfall, the trend of N2O concentration in the soil profiles and N2O emission flux changes with the time were similar to that temporal rainfall variation pattern. Incubation test showed that when soils have same water filled pore space (WFPS) content, the influence on N2O emission of soil from wet to dry is bigger than that from dry to wet. For the former, the biggest N 2O emission takes place at 70% soil WFPS instead at soil saturated, and after that N2O emission will decrease with the soil WFPS decrease and for the latter, soil N2O emission increases with the soil WFPS content increase. The control plot has the same tread as the fertilized plot but the curve is much more flatter than applied N treatment.