Abstract: In order to provide technical support for air pollution control and air quality forecast and early warning, it was necessary to study on spatio-temporal characteristics of PM_2.5 concentration and pollution weather types in region. Based on the daily air quality monitoring data and correlative meteorological data of 14 cities in Guangxi from 2015 to 2016, the air quality overview and basic characteristics of air pollution of Guangxi from 2015 to 2016 were analyzed. Methods of empirical orthogonal function (EOF) analysis, backward trajectory clustering analysis were adopted to characterize the spatio-temporal mode of ρ(PM_2.5) of Guangxi, the weather type and the variation characteristics of air quality were analyzed in different pollution processes by using the 24 times regional pollution process (AQI>100, contiguous cities ≥ 3), which occurred during the two years. The results indicated that PM_2.5 is the primary pollutant of air pollution in Guangxi, the ρ(PM_2.5) was high in the north and low in the south, monthly variation of ρ(PM_2.5) followed a V-shaped distribution; The results of EOF and backward trajectory clustering analysis showed that, there were three main spatio-temporal modes of ρ(PM_2.5), variance contribution of the three modes were 78.9%, 5.7% and 3.7%, which reflects basically the main characteristics of the variation of ρ(PM_2.5) in Guangxi. The backward trajectory clusterings of Guilin and Yulin cities from 2015 to 2016 were well explained that North-South concentration of the second mode and East-West concentration of the third mode showed the characteristic of anti-phase distribution; There were 10 kinds of regional pollution weather types of 14 cities in Guangxi during the two years, weak cold high pressure (24.4%), uniform pressure field (20.2%), back of high pressure (16.1%) and back of high pressure combined with southwest warm low (8.5%) were typical weather types which caused air pollution in large range. Research shows that air pollution in Guangxi has got the feature of regional, seasonal and south-north transport of ρ(PM_2.5), there were certain regularity in the weather situation of pollution process.