Abstract: Because primary radar plays an important role in averting flight conflict between civil aviation and military aviation, some internal airports installed primary/secondary radars. Some air traffic control primary radars use pulse compression technique. The biggest advantage of it is the increasing radar range and improving range resolution. This paper introduces conception of Linear Frequency Modulation (LFM)and pulse compression, analyzes the frequency spectrum and pulse compression principle, summarizes the advantages of pulse compression technique and gives an application model.