With the improvement of frequency and bandwidth of fuse, the accuracy, target identification ability and anti-interference ability of detector are correspondingly improved. Therefore, the research on D-band detector for active terminal-sensitive projectile is carried out. Based on 120 GHz transceiver chip TRA_120_001, a D-band detector is designed. In order to improve the detection distance, a semi-spherical lens antenna is fabricated. The experimental scene of rotating scan falling with angular reflector as the target is built. In the experiment, the detector sets the target direction, gives the trigger signal, realizes the detection function and verifies the ability of range measurement.