According to the homing principle of semi-active laser guided weapons,the main parameters which affect the simulation confidence in the performance test of hardware-in-the-loop simulation are analyzed.The laser target simulator based on the transmission-mode structure is designed.Using this system it can generate laser beams with sparkle size of 0.1 mm to 20 mm.The central point aberration is ±9 mm.The energy range is bigger than 50dB.An experimental system was set up.The results show that the range of laser target simulation is increased effectively by using this transmission-mode structure,while it is more convenient to simulate various characteristics of the laser target.