The front end RF for radiated radar target simulator was designed and integrated in this paper. This simulator was operated on the L/S/X three bands, and it supported the CW and pulse operation. It generated multi-targets in high precision. The plug module structure design improved the EMC and the extension performance of the RF front end. The measured results of the system are better than the target. Furthermore, this RF front end supports the radar simulator finish the target simulating for the real radar successfully, which verifies the performance of this radar simulator.