Abstract: The variation law of echoed laser power in the process of fuze encounters the target was analyzed, and a method of simulating the rapid change of echoed laser power by changing the supply voltage and the pulse signal's width of pulse semiconductor laser was put forward. PFGA was used as the controller to command the high speed digital-analog converter, in order to realize fast switching of semiconductor laser drive circuit's supply voltage in submillisecond level. Experiment results show that the laser power can be adjusted rapidly and accurately within 100 <i<μ</i<s.