AbstractAimed at the problem of false alarm and missing alarm caused by information uncertainty existing in the fire alarm system, Bayesian network (BN) is proposed to analyze fire alarm system. The paper elaborates the internal logic relationship between the fire alarm and the physical-chemical characteristics generated in the process of fire burning by analyzing fire mechanism. Based on defining node variables in BN, multi-sensor Bayesian network model for the fire alarm system is established in Netica. Probabilistic inference and sensitivity analysis of finding node verified that analyzing fire probability through the multi-sensor Bayesian network model is feasible and effective.