Based on the daily average concentration of sulfur dioxide (SO2), nitrogen dioxide (NO2) and respirable particulate matter (PM10) from 2001 to 2010, the atmospheric environment quality over the past 10 years in Xi'an was comprehensively evaluated. The process of the evaluation method involves the follow key procedures. First, the pollution factors are put in order by using the evaluation factors dynamic sorting method for determining the importance of each factor. Second, the Analytic Hierarchy Process (AHP) method is used to determine the weight value of every factor. Finally, the composite index, which represents the environment comprehensive quality, is calculated by weighted average method. The results can provide scientific basis for the related departments to understand the atmospheric environment comprehensive quality in Xi'an.