A laser signal simulation system based on a backward transmission screen is proposed. The system is used to test the performance of laser-guided weapons in a laboratory environment. The system enables the simulation of the laser-guided weapons by controlling the movement of a two-axis motor and changing the laser intensity. In addition, using the ScramNet ring topology, real-time hardware-in-the-loop simulation (HILS) can be implemented through the system. In terms of the scale and the complexity of the system, this laser simulator is relatively more compact and simpler than other previously reported cases. Moreover, the diffusivity of the laser beam can be highly improved through the transmission screen. This implies that diffused laser signals reflected from a target can be accurately simulated through the system. A closed-loop HILS for a target tracking scenario is done using the laser signal simulation system. The system satisfies the designed requirements and proves itself to be an innovative simulation method for laser-guided weapons with semiactive seekers.