In　this　paper,　a　coupled　MM5-CMAQ　modeling　system　was　employed　to　investigate　the　PM10　pollution　issue　in　Beijing,　China,　with　a　focus　on　assessing　the　effects　of　different　restriction　policies　implemented　during　and　after　the　2008　Olympic　Games.　The　simulations　under　designed　scenarios　were　implemented　over　a　2-level　nested　grid　domain　for　comparing　the　difference　of　PM10　concentrations　under　restriction　and　no-restrictions　situations.　The　restriction　measures　include　alternate-day　vehicle　driving,　construction　activities,　trans-boundary　emissions　from　neighboring　provinces,　and　vehicle　restrictions　during　the　post-Olympic　period.　Meteorological　contributions　to　the　air　quality　improvement　were　also　examined.　The　results　show　that　significant　improvement　of　air　quality　in　Beijing　during　the　2008　Games　was　attributed　largely　to　these　restriction　measures,　although　favorable　weather　conditions　play　an　important　role.　Also,　during　the　post-Olympic　period,　daily　vehicle　restrictions　implemented　temporarily　under　extreme　weather　conditions　played　a　crucial　role　in　alleviating　Beijing＇s　air　pollution.　Beijing　not　only　needs　to　take　continuing　efforts　to　addresses　its　own　PM10　problem,　but　also　has　a　clear　self-interest　in　demanding　better　environmental　performance　from　neighboring　provinces.　It　is　suggested　that　Beijing　would　work　collectively　with　neighboring　provinces　to　develop　a　long-term　multi-region　initiative　and　strategy　aimed　at　emission　reduction　for　providing　the　citizens　in　this　region　a　healthy　and　clean　air　in　the　long　run.