Abstract: To make an in—depth analysis on the causes of the major fire accident on “4·17” in Wuyi, the process of the fire was restored through FDS reconstruction simulation of the fire scene. Analyzes fire temperature, smoke, oxygen concentration, heat release rate, and parameters of different sections; and makes comparative analysis on the key disaster—inducing factors of the fire accident combined with Pathfinder evacuation simulation analysis. The verification of the results showed that the fire led to heavy casualties mainly because the nature of the use of the workshop was changed without authorization, which increased the fire risk, and the corresponding fire protection design improvement was not made. Among them, the rapid spread and diffusion of fire smoke caused by the open stairway connecting the atrium and the workshop between the first and second floors were the key factors leading to the fire. Second, when the fire happened, on—site personnel failed to find it, evacuate, and escape immediately, which was another important reason for the casualties.

Key words: fire, fire source;FDS, major fire, numerical reconstruction