The three!axis simulator is one of the most important equipments of semi!physical simulation system for a laser !guided bomb seeker. The design and realization of the real !time control system are discussed according to the requirements of the real !time control of high precision three !axis simulator. Compared with those of Windows - NT in time resolution, the real !time characteristics of RTX are presented. Experiments are performed and the results show that it runs in high real !time performance and works steadily and reliably.