世界城市人口的迅速增长导致车辆不可避免的增多,给城市带来了交通拥挤、环境污染和能源危机等许多问题。据专家预测，到2010年，世界人口将超过60 亿，而百万人口以上的大城市也将突破400个。而城市中传统的地面交通，如公共汽车、无轨电车则因运量小、速度慢，将无法适应城市客运的需要。地铁则因运量大、无污染、速度快、准时、舒适、方便和节能等特点，得到飞速发展。因此，发展城市地铁交通，缓解车辆拥挤的问题越来越引起世界各国的高度重视。 随着我国经济的不断地发展，城市化进程的不断加快，城市地铁作为缓解城市交通压力的有效方法在我国得到了迅速发展，我国已建有地铁或已开工建设地铁的城市有：北京、上海、广州、天津、大连、深圳、成都等。但随着城市地铁建设的飞速发展，火灾问题也日益引起人们的广泛关注。由于地铁环境不同于地上建筑，也有别于一般的地下建筑，因此，这个问题已成为当今城市地铁环境中的热点问题，国外对地铁环境中的火灾问题关注的较早，着手进行研究的工作开展的也较为全面细致，但国内由于种种制约因素，在此相关问题上的研究一直相应的有所滞后。 为了探讨地铁站火灾烟气的发展流动规律，本文根据我国典型的双层岛式地铁车站的建筑结构模式建立了物理数学模型，并采用计算流体力学软件对地铁站站台层列车着火及站台起火时的烟气扩散及温度分布进行了三维场模拟，分别采用国内、国外两种疏散计算标准，针对相应的危害环境，分别得出人员可利用的逃生时间 与人员安全疏散所需时间 ，将 与 相比较，得出在此火灾条件下，按照国外计算疏散时间的方法所得到的疏散时间不满足我国GB50157-2003《地下铁道设计规范》第12.2.11条规定，需要进一步加宽站台层至站厅层楼梯宽度。 本文采用数值模拟研究，通过一定程度的简化措施，模拟出了火灾状况下的烟气及温度分布，为今后地铁环境防火减灾研究提供了一定的帮助。

With the population of the city in the world quickly increasing, more and more vehicles bring out such problems：the traffic jam, the pollution of the environment and energy crisis, etc. Estimated by The expert that In 2010,The population of the world will exceed 6 billion , the number of city which have more than million people will also exceed 400.The traditional transportation such as buses and trolley bus will be abandoned .Because of the big carrying capacity, free from pollution ,the quicker speed, on time, comfortable, the convenience and saving energy, subway is soon developing .In a word, the country in the world paid more and more attention on developing subway in order to ameliorate the traffic jam. With the rapid progress of the economy and the urbanization in China, the subway as an effective method to solve the problem of traffic is developing quickly in our country. The city in China already having the subway or have started to construct subway：BeiJing, Shanghai, Guangzhou, Tianjin, Dalian, Shenzhen , Chengdu etc. Because the subway environment differs from that in the building, also is not the same as that of underground building , therefore, this problem has nowadays become the focus. Airiness in the environment and a fire problem arose the attention early in the abroad,the research almost covers all the aspects. However, because of all kinds of factors, the related research on the problem lag behind in China. In order to discuss the flowing rule and the control of the smoke, a physical model of a two-layer and island type subway station is established in the paper, The three-dimensional field simulation about the spread of smoke when a train catches fire in the subway platform is carried out by computational fluid dynamics，adopt domestic and foreign dispersion standard to aim at the environment, get —personnel available safe egress time and —required safe egress time to compare, under the condition of this fire, according to the foreign calculation method, evacuation time dissatisfied our country GB50157-2003 《subway design norm》12.2.11 regulation rules, need to further widen steps width from the website layer to go to station hall floor . The method to study is numerical simulation. Through some simplifying, and simulating, the expansion of the smoke and temperature during the fire are gotten, The analysis of results is also valuable for researching and operating of other subway.