Perimeter intrusion defense system based on fiber Bragg grating (FBG) is a new generation fiber optic perimeter security safety system.The FBG intrusion detection system can intelligently determine location with high performance.The false alarm rate (FAR) is one of the most fundamental pa rameters of intrusion system. It is related to a lot of factors such as the sensitivity of FBG sensor,the ins tallation environment and installation quality.In this paper,in a fence with FBG intrusi on system,using FBG wavelength peak in time domain together with frequency domain band energy integral method to improve the anti-jamming performance algorithm i s presented for recognition of real intrusion and non-intrusion,especially for EMU-induced false alarm events.We use time-frequency analysis method of short-time Fourier transform (STFT),with Hanning window length of 128,the windo w sliding points of 64,So the integration of the energy within the frequency range of the wavelength peak corresponding to the STFT of 1～5Hz is obtained,in or der to identify the invasion of non-invasion events.According to the results of data analysis and practical application of this method,assuming the premise of a false negative r ate(FNR) of zero,the EMU caused FAR is reduced by 80%.This algorithm greatly improves the system ability of resistance to environmen tal disturbance.