Occupants　often　perform　many　types　of　behavior　in　buildings　to　adjust　the　indoor　thermal　environment.　In　these　types,　opening/closing　the　windows,　often　regarded　as　window-opening　behavior,　is　more　commonly　observed　because　of　its　convenience.　It　not　only　improves　indoor　air　quality　to　satisfy　occupants＇　requirement　for　indoor　thermal　comfort　but　also　influences　building　energy　consumption.　To　learn　more　about　potential　factors　having　effects　on　occupants＇　window-opening　behavior,　a　field　study　was　carried　out　in　an　office　building　within　a　university　in　Beijing.　Window　state　(open/closed)　for　a　total　of　5　windows　in　5　offices　on　the　second　floor　in　285　days　(9.5　months)　were　recorded　daily.　Potential　factors,　categorized　as　environmental　and　non-environmental　ones,　were　subsequently　identified　with　their　impact　on　window-opening　behavior　through　logistic　regression　and　Pearson　correlation　approaches.　The　analytical　results　show　that　occupants＇　window-opening　behavior　is　more　strongly　correlated　to　environmental　factors,　such　as　indoor　and　outdoor　air　temperatures,　wind　speed,　relative　humidity,　outdoor　FM2.5　concentrations,　solar　radiation,　sunshine　hours,　in　which　air　temperatures　dominate　the　influence.　While　the　non-environmental　factors,　i.e.　seasonal　change,　time　of　day　and　personal　preference,　also　affects　the　patterns　of　window-opening　probability.　This　paper　provides　solid　field　data　on　occupant　window　opening　behavior　in　China,　with　high　resolutions　and　demonstrates　the　way　in　analyzing　and　predicting　the　probability　of　window-opening　behavior.　Its　discussion　into　the　potential　impact　factors　shall　be　useful　for　further　investigation　of　the　relationship　between　building　energy　consumption　and　window-opening　behavior.