In this paper, a new method is proposed to analyze the vulnerability of fire spreading in building. This study is based on the application of the artificial intelligence using fuzzy logic. After an overview of the phenomenon of spreading [1] [2], an identification of the various parameters that may influence this phenomenon has been achieved and by applying fuzzy logic technique, the vulnerability analysis has been established. This study represents an important step for modeling a decision support system in order to optimize the fire risk in a building.