With the development of antenna manufacturing technology, ultra-wideband technology, synthetic aperture technology and signal processing technology, the radar volume is decreasing, and radar detection accuracy and imaging resolution are greatly improved. Furthermore, radar began to be active in the civilian field. New civil radars which are used in penetrating imaging, microwave remote sensing imaging, landslide monitoring and airport foreign object debris detection are developing rapidly. In order to make civil radars with higher and more stable performance in a complex natural environment, radar signal processing technology has been innovating. Here, we introduce the new trends and new technologies of civil radars, as well as the key issues and solutions of signal processing for the wallpenetrating radar, the small SAR, the slope radar and the foreign object debris(FOD) radar.