Abstract: Since laser beam has great brightness and good orientation, there are more and more applications in the industrial and military fields. Based on the merits of laser, the laser jamming to the target acquiring and tracking system with modulator was studied by experiment and simulation. In these experiments, the key parameters of laser system are output power and the laser pulse frequency. The laser jamming mechanism was studied by changing the output power and pulse frequency. After the experiments, the detailed analysis was done and some valuable conclusions were made. And based on the laser pulse reflected from the modulator surface, the rotate speed of the modulator was determined.