A　coupled　MM5-CAMx　air　quality　modeling　system　was　used　to　simulate　SO2　concentrations　in　Beijing,　China　during　the　heating　season.　Particulate　matter　source　apportionment　technology　was　employed　to　investigate　the　apportionment　of　SO2　sources　in　the　study　area.　Comprehensive　analysis　of　the　industry　and　region　revealed　that　the　most　important　SO2　contributors　were　publicly　and　privately　supplied　heating　emission　sources　and　other　industry　emission　sources　from　the　urban　areas　of　Beijing,　with　66.1　%　of　the　emission　source　contribution　ratio.　Four　SO2　emission　reduction　scenarios　based　on　our　SO2　source　apportionment　research　were　established　to　assess　the　potential　for　improving　the　SO2　air　quality　in　Beijing　during　the　heating　season.　By　weighing　the　desired　SO2　improvement,　the　availability　of　technology,　and　economic　considerations,　a　suitable　SO2　reduction　plan　was　able　to　be　recommended　for　Beijing　city.