In this paper, a triple-mode filtering patch antenna with high selectivity is proposed. The patch serves as a radiator that only loads two pairs of symmetrical slots without extra elements. On the one hand, these slots reduce the frequencies of high-order modes TM02 and TM12 modes together with TM10 mode to form the operating band to increase the bandwidth. On the other hand, these slots excite two radiation nulls near the passband due to radiation cancellation caused by the surface current, thus improving the out-of-band selectivity. Finally, a filtering patch antenna is designed and simulated. The simulated results indicate that the filtering antenna operates at 3.5GHz with a fractional bandwidth of 7.14%. Two radiation nulls are located at 3.1GHz and 4.0GHz, resulting in a high selectivity.