Theoretical analysis is made to the principle of laser jamming on long wave infrared detecting equipment.The environment for laser jamming experiment was set up, through which the crosstalk effect of 9.4 μm laser with different parameters of power, frequency and angle of divergence on detecting equipment was studied by experiments.The crosstalk level was scaled by spot of laser on detector and contrast ratio of the spot and background.It is concluded that the crosstalk effect is determined by laser power density on the detector.It is obtained through experiment that when laser frequency is 20 kHz, the jamming threshold of long wave infrared detecting equipment is 39.89 mW/cm2, which is consistent with the theoretical analysis.