The　typical　subway　island-platform　of　Beijing　as　research　object　was　present　in　the　article.　Taking　k-epsilon　two-equation　turbulence　model　and　giving　boundary　conditions　of　piston　wind　and　train　heat　load　change　with　the　time,　adopting　numerical　method　simulates　air　distribution　of　air-conditioning　and　ventilation　system　in　subway.　The　results　indicate　that　piston　wind　effect　has　significant　impact　on　the　area　of　platform　entrance　and　staircase　entrance　while　station　with　safety　doors　can　obstruct　piston　effect　at　a　certain　degree.　Simultaneity,　the　supply-　exhaust　air　system　offers　relatively　uniform　temperature　and　velocity　field,　which　meets　requirements　of　transitory　comfort　for　passengers.　It　is　found　that　numerical　simulation　method　can　simulate　and　forecast　air　distribution　of　air　conditioning　and　ventilating　system　in　subway　station.　In　conclusion,　it　can　provide　the　reference　for　optimizing　air-conditioning　and　ventilation　system,　improving　thermal　environment　designing　of　subway　station.