This paper proposes a design of ultrabroadband reflective polarization convension metasurface composed of the shape of “H” metallic periodic structure, a layer dielectric and a metallic plate ground. Almost an equal magnitude and a 90° phase difference generated between the two orthogonal electric components of the reflected waves can be reached by changing the size of the metasurface cell. The simulation and measurement show that this device can allow linear to convert circular polarization from 6.40 GHz to 15.40 GHz and 17.49 GHz to 18.14 GHz, while the axis ratio is less than 3 dB. This can also realize more than 80% polarization conversion ratio from 15.81 GHz to 17.26 GHz under bothxandypolarized incidence. The proposed polarization convension is characterized by a compact structure and simple geometry, a low loss to energy in ultrabroadband, using more unit cell in the available space. This design is of great value to electromagnetic control and design of new antennas.