Abstract: Aiming at the solution of sidelobe problems of phase-coded radar signals, a novel method of code agility is proposed here. Different codes selected randomly are transmitted from pulse to pulse, and the return waves are projected to the radar line of sight after matched filtering for each echo and DFT processing for each range cell. A criterion for code selection is established as well. Theoretical analysis and experiments indicated that this technique suits for various biphase codes or polyphase codes, with perfect effect of sidelobe suppression. In addition, the capability of small targets detection is improved. Furthermore, good reduction performance can be retained even if target return waveforms are eclipsed to a great extent due to high duty cycle.