In order to make appraisal of the combat capability for laser-guided weapons in internal field, the laser signal simulation system was designed. First of all, for the composition of the laser signal simulation system and its working principle, the internal field simulation and equivalent methods of laser signal divergence angle, energy and direction were analyzed respectively, and the dynamic adjustment of the three devices was calibrated. The experiment results show that: The relative error of dynamic simulation of the laser signal spot diameter is less than 2.5%, the dynamic adjustment error of energy attenuation is less than 0.2 dB, dynamic adjustment error of azimuth and elevation are respectively less than 1.3 mrad, 0.6 mrad. The simulation system has been applied in the photoelectric countermeasure simulation project, and this simulation system can provide high degree of laser signal simulation for laser-guided weapons qualification test.