The invention discloses an infrasound event detection method and system. According to the method and system, a wavelet packet decomposition method is used, reconstruction is carried out in different frequency bands after decomposition of an infrasound signal to be detected, Fisher detection is carried out on a reconstruction signal in each frequency band, each Fisher value is stored as an attribute in the same time window of multiple array elements, and a 2D Fisher attribute distribution map in a time-frequency plane is generated from calculation results. The time sale related to signal detection is taken into consideration, certain scale threshold serves as a signal measuring standard, influence of ambient noise on calculation of the Fisher attribute value is reduced, and thus, the missedalarm rate and false alarm rate of infrasound event detection are reduced, and the infrasound event detecting efficiency and precision are improved.