Beijing　in　China　is　facing　a　serious　air　pollution　problem　which　severely　impacts　the　daily　life　quality.　How　to　monitor　the　air　quality　in　real-time　with　a　big　coverage　of　Beijing　city,　and　automatically　process　the　big　data　is　now　becoming　a　hot　research　topic.　Air　quality　sensors,　such　as　CO,　SO2,　NO,　NO2　and　PM2.5　sensors,　can　accurately　detect　the　level　of　air　pollution　which　may　contain　different　kinds　of　tiny　particles.　By　using　Internet　of　Things　(IOT)　technology,　information　can　be　transferred　from　IOT　sensor　nodes　to　the　information　processing　center　through　different　wireless/wired　networks.　This　paper　aims　to　build　a　prototype　system　by　hierarchically　deploying　terminal　sensor　nodes　inside　the　smart　buildings　of　each　floor　and　data　collection　units　and　routers　in　the　open　spaces　between　smart　buildings,　and　transferring　the　sensor　thing　data　back　to　the　information　processing　center　for　real-time　display.　In　this　implementation,　all　sink　nodes　send　out　air　quality　detection　information　to　the　information　processing　center　through　ZigBee　wireless　protocol.　Information　processing　center　receives　and　analyzes　real-time　information　being　collected　from　the　sensors,　stores　all　information　to　the　database.　Through　reading　IOT　thing　data　stored　in　the　database,　web　front-end　system　will　draw　real-time,　high-quality　air　quality　monitoring　maps　of　the　inside　and　outside　of　the　buildings.　Further,　a　detailed　system　power　optimization　is　also　presented.