Abstract: With the development of radar technology, the target and environment simulators which make use of computer simulation technique and high speed digital circuit technique play a more and more important role in the development of the radar. This paper describes briefly the basic composition of the real time radar electromagnetic environment simulator and discusses the implementation methods of different requirements. It introduces mainly one kind of large-scale real time radar electromagnetic environment simulator and describes in detail the composition of the simulator, the functions of every part and the specific implementation of real signal generlization.