Abstract: In the obverserv ational result of the atmospheric N2O concentration in some unpolluted regions of China from May 1993 to July 1995, They show that the average mixing ratios of N2O over agricultural fieldes(maize and wheat) are from 322.1 to 343.4 ppbv (10-9v/v). There are larger value and variation of mixing ratio of N2O due to emission of N2O from fertilized soils. The mean mixing ratios of N2O at Linan and Longfengshan Background Air Pollution Monitoring Station and Waliguanshan Global Atmosphere Watch Baseline Observatory (WMO/GAW) are 318.8±8.4 ppbv, 317.4±4.7 ppbv and 314.0±4.2 ppbv, respectively. The distribution and variation of N2O were disscussed. Additionally, the sampling technique and measured method of mixing ratio of N2O were specially analysed and assessed.