Abstract: In this paper, a novel harmonic suppression unit radome based on metamaterial is designed. The radome consists of a multi-layer structure. For arranging more periodic units in the limited size range of an antenna unit to reduce the influence of the edge effect, a complementary subwavelength unit is designed. The total thickness of the radome is less than 5 mm, and is connected by the PMI foam with horn antenna. With laser ablation technology two kinds of radome were fabricated. The transmission coefficient test and the harmonic suppression test of the array antenna array are carried out. The results show that the radome has the insertion loss of 0.3 dB in band, the suppression of the second harmonic 20 dB and the suppression of the third harmonic 30 dB.