The invention discloses a multi-information fusion fire hazard detection method, comprising the following steps: preprocessing is carried out on a fire hazard detection signal sequence obtained by site period sampling, and unreasonable data generated by normal environmental change is removed; a gray model GM (1, 1) is built according to the preprocessed original fire hazard detection signal sequence, and fire hazard detection signal data at follow-up time points is predicted, so as to obtain an equal dimensionality new information gray prediction model; the original hazard detection signal sequence is utilized to carry out posterior check on the fire hazard detection signal data obtained by prediction, so as to check whether the fire hazard detection signal data generated by prediction ongray prediction model is qualified or not; and a diagnosis neural network is utilized to diagnose the qualified fire hazard detection signal time sequence data, so as to obtain a fire hazard detection result. By means of the invention, reliable fault diagnosis can be provided and the false alarm rate of fire detection result can be reduced.