Abstract: To effectively attack the armed helicopter using air defense rocket with aimed warhead, the detection mechanism of six laser range-finders and its application for the optimum time delay of aimed warhead were analyzed. The mathematic model to calculate the optimum time delay based on the information provided by laser range-finders was set up. Simulation results in the Matlab software demonstrated the effective and feasibility of the proposed method when the armed helicopter was specified as the target. This analysis provides a theoretical foundation for developing air defense rocket.