Abstract: Environmental security is an important part of the national security,and is noticed world-widely.Based on the security situation of atmospheric environment,adopting pressure-state-response(PSR) model,an assessment system composed of 4 levels and 3 aspects was brought forward.The indexes and indicators were confirmed from pressure,state and response of atmospheric environmental security and the criterion was established.Weight value of each indicator was calculated using analytic hierarchy process(AHP).And the score of each index was gained with sum based on the weight value of each indicator.Using the established assessment system,the authors assessed the atmospheric environmental security of each province in China.The results showed that the atmospheric environmental security has flake-like distributions,and the situation is severe in most provinces.Meanwhile,the management of environmental security should be strengthened.From the analysis on regional difference,East China was better than others. From the analysis on key factors,the consumption of energy was the key factor in North China,and acid rain influenced the atmospheric environmental security seriously in South China.In general,the atmospheric environmental security will be better in the future.