In recent years, the high concentration of air pollutants has seriously affected people’s daily life. So, it is important and necessary to know the spreading PM_2.5 concentration and its correlation with other pollutants. The data presented in this paper was received from 13 monitoring stations by a typical northern city of Xi’an in China for the whole year of 2017. The concentration distribution of PM_2.5 and its variations with the season, month and day were analyzed. Also the average correlation between PM2.5 and CO, SO₂, NO₂, O₃ and PM₁₀ was studied. The results showed concentrating PM_2.5 was consistent with the seasonal, monthly and daily trends. The concentration of PM_2.5 showed a low in summer and autumn. While the concentration of PM_2.5 was higher in spring and winter, and the highest concentration was in winter. The daily variation distribution of PM_2.5 showed a double-peak variation characteristic. The concentration of PM_2.5 reached a peak between 8:00-9:00 in the morning and 22:00-23:00 in the evening. Particles of Xi’an in atmospheric were mainly fine particles. There was a strong correlation between PM_2.5 and CO, SO₂, NO₂, PM10, but a negative correlation between PM_2.5 and O₃. A multivariate linear regression model with the pollutant concentration of CO, SO₂, NO₂ and PM₁₀ was established. This study helps to understand the distribution of PM_2.5 and its correlation with other pollutants of Xi’an, and further supplying important support for the targeted controlling approach of fog and haze.