以火灾成长概率和火灾发生后的过火面积为评价指标，探讨对建筑火灾过火面积的预估方法。依据火灾动力学和火灾发展过程中不同阶段的特点，将火灾由初期发展蔓延到整个防火分区的过程划分为4个阶段，采用概率论和事件树的分析方法，得到了每个阶段的火灾成长概率。根据不同阶段火灾的特点，求得了各阶段火灾的临界时间，并以此为基础对火灾发生后建筑物平均过火面积进行了预估。

Based on fire growth probability and burned area, the method for evaluating burned area in building fire is presented in this paper. According to fire dynamics and different characteristics in fire growth process, the process is divided into four phases. By means of probability theory and event tree analysis, fire growth probability and critical time of every phase are calculated. Average burned area of building can be evaluated.