Based on daily PM2.5 concentration data during 2014-2017, the annual and monthly variations of PM2.5 concentration were analyzed in Xi’an, and in heating and non-heating seasons its difference was obvious. Combined with daily meteorological elements observations from  meteorological stations, the correlation between meteorological elements and PM2.5 concentration in different seasons was analyzed. The hourly PM2.5 concentration data of 13 air-quality automatic monitoring stations in 2017 were used to analyze the spatial distribution and diurnal variation of PM2.5 concentration in Xi’an. The main conclusions are as follows: The PM2.5 concentration showed a U-shaped characteristic within a year, which was higher in winter but lower in summer. The difference of PM2.5 concentration in recent years was mainly in January, February, November and December，during this period, the wind speed, precipitation and cold air activity frequency had some influence on PM2.5 concentration. The days of PM2.5 exceeding standard in heating season and its ratio to PM2.5 exceeding standard days in the whole year increased but both of them declined in non-heating season. The difference of PM2.5 pollution in various regions was larger in winter but it was smaller in summer. The PM2.5 concentration presented obvious diurnal variation, and its fluctuation curve was M-shaped. The correlation between meteorological factors such as temperature, relative humidity, wind speed and precipitation and PM2.5  concentration was different in different seasons. High level PM2.5 pollution was more likely to occur on those days with low temperature, high humidity, low wind speed and less precipitation. The range of basic meteorological elements under different levels of PM2.5 pollution condition obtained by statistics had some indicative significance for the air quality forecast of PM2.5 pollution.