In　this　study,　an　analysis　framework　based　on　the　regular　monitoring　data　was　proposed　for　investigating　the　annual/inter-annual　air　quality　variation　and　the　contributions　from　different　factors　(i.e.,　seasons,　pollution　periods　and　airflow　directions),　through　a　case　study　in　Beijing　from　2013　to　2016.　The　results　showed　that　the　annual　mean　concentrations　(MC)　of　PM2.5,　SO2,　NO2　and　CO　had　decreased　with　annual　mean　ratios　of　7.5%,　28.6%,　4.6%　and　15.5%　from　2013　to　2016,　respectively.　Among　seasons,　the　MC　in　winter　contributed　the　largest　fractions　(25.8%similar　to　46.4%)　to　the　annual　MC,　and　the　change　of　MC　in　summer　contributed　most　to　the　inter-annual　MC　variation　(IMCV)　of　PM2.5　and　NO2.　For　different　pollution　periods,　gradually　increase　of　frequency　of　S-1　(PM2.5,　0　similar　to　75　mu　g/m(3))　made　S-1　become　the　largest　contributor　(28.8%)　to　the　MC　of　PM2.5　in　2016,　it　had　a　negative　contribution　(-13.1%)　to　the　IMCV　of　PM2.5;　obvious　decreases　of　frequencies　of　heavily　polluted　and　severely　polluted　dominated　(44.7%　and　39.5%)　the　IMCV　of　PM2.5.　For　different　airflow　directions,　the　MC　of　pollutants　under　the　south　airflow　had　the　most　significant　decrease　(22.5%similar　to　62.5%),　and　those　decrease　contributed　most　to　the　IMCV　of　PM2.5　(143.3%),　SO2　(72.0%),　NO2　(55.5%)　and　CO　(190.3%);　the　west　airflow　had　negative　influences　to　the　IMCV　of　PM2.5,　NO2　and　CO.　The　framework　is　helpful　for　further　analysis　and　utilization　of　the　large　amounts　of　monitoring　data;　and　the　analysis　results　can　provide　scientific　supports　for　the　formulation　or　adjustment　of　further　air　pollution　mitigation　policy.　(C)　2019　The　Research　Center　for　Eco-Environmental　Sciences,　Chinese　Academy　of　Sciences.　Published　by　Elsevier　B.V.