Abstract: This paper presents a low-profile and high out-of-band suppression filtering metasurface antenna array. The antenna element is composed of a metasurface structure, a defected ground structure and an I-shaped stub. The defected ground structure generates a radiation zero at the upper passband edge, enhancing the upper stopband suppression level. In addition, the I-shaped stub not only generates a radiation zero at the lower passband edge, further improving the lower stopband suppression level, but also generates a radiation zero within the passband, broadening the operating bandwidth. To enhance the gain of the filtering antenna, a 1×4 filtering metasurface antenna array for the n257 band (26.5 - 29.5 GHz) is proposed, with a profile height of 0.11 λ0 (λ0 is the wavelength corresponding to the center frequency of 28 GHz). The measured results show that the -10 dB impedance bandwidth of the antenna array is 13% (26.2 - 29.8 GHz), the maximum gain within the passband is 10 dBi, and the out-of-band suppression level can reach 23 dB. This antenna has the characteristics of low profile, compact structure and high out-of-band suppression, and thus has potential application value in the 5G millimeter-wave band.