PM2.5 and PM10 mass from quartz-fiber weight were obtained in Xian for two weeks of every month corresponding to January,April,July and October during 2010 at upwind district of Gaoling county (GLC),downwind background station of Black river reservoir (BRR) and four urban sites.Annual average PM2.5 and PM10 mass concentrations were 140.9 ± 108.9 μg m-3,257.8 ± 194.7μg m-3,respectively.Seasonally,high concentrations in wintertime and low ones during summertime were attributed to seasonal variations of meteorological parameters and cycle changes of precursors (SO2 and NO2).Stepwise Multiple Linear Regression (MLR) analysis indicated that relative humidity is the main factor influencing on meteorological parameter.Sulfate of SO2 oxidation products are concentrated in fine mode of PM2.5 and nitrate of NO2 oxidation in coarse mode of PM10.Entry MLR analysis suggested that SO2 and NO2 contributed 48.6% and 33.9%,and 17.5% and 0.7% of the total PM2.5 and PM10,respectively.Trajectory cluster results indicated long distance air mass from northwest in winter (82.1%) and in spring (67.9%),and short distance from surrounding provinces in summer (62.5%) and autumn (73.2%).Potential Source Contribution Function (PSCF) analysis showed three day Dust storm (DS) came from Taklimakan Desert in Xinjiang and Gobi Desert in Inner Mongolia in spring.Remote sensing retrieval (OMI UV Aerosol Index (AI),OMI tropospheric NO2 column of Aura and Aerosol Optical Depth (AOD) of MODIS TERRA) from Giovanni online tools of NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) were verified results of observation on the ground to some extents.