Abstract: In this paper, a filtering antenna with harmonic suppression and high selectivity is designed. Two slits are etched on the square microstrip patch and a split ring defected ground structure（DGS）is etched on the ground, which introduces two radiation nulls and improves the selectivity of filtering antenna. By etching two dumbbell-shaped DGS on the ground plate and loading a circle stub on the feeder, the harmonic was suppressed even up to 12 GHz（4.8f₀）. The measured results show that the designed filtering antenna works at 2.34 GHz～2.42 GHz, with two radiation nulls at 2.28 GHz and 2.70 GHz and the reflection coefficients are more than-4 dB from 3 GHz to 12 GHz.