The simulation of flight checking is of an important value for the real flight checking. According to the technology system and navigation principle of the microwave landing system (MLS), a laser simulation flight checking hardware-in-the-loop simulation system of MLS based on scale model is designed and established. The realization theory and technology of the environment model of the simulation system are studied. The technology of preparation of some typical materials is researched. Finally, a scale model of a real airport is set up, and a model test is made. The test result indicates the validity of the model test system of MLS.