Abstract: The operation principle of the passive angle jamming system (optical fiber laser jamming system) by changing the laser guiding angle was presented, system jamming effectiveness parameters such as the power ratio and the delay time were discussed. The analysis shows that the laser power reflected from the decoy can meet the requirement if the coverage of the optical fiber receiving system and reflectance of the decoy are properly selected, and the delay time of several microseconds is far less than the gate width of the target required by seeker, which makes the incident probability of laser echo into the gate from the decoy quite high. The feasibility of the jamming system is proved. Other measures such as the camouflage or displacing laser into open space could make the jamming system more effective.