An efficient terahertz (THz) metamaterial linear polarization converter is proposed. The structure consists of three layers of metal-dielectric-metal, including an anisotropic super-surface based on bimetallic arc structure as the top layer and a dielectric layer and a metal plate as middle layer and bottom layer, separately. The numerical analysis results show that broadband polarization conversion of a linearly polarized wave in the terahertz band is realized using the structure proposed. The polarization conversion ratio of the linearly polarized wave is more than 90% across a wide frequency range from 1.21 THz to 2.82 THz. The ratio of bandwidth to central frequency can reach 80%. The mechanism of high polarization conversion rate and broadband is analyzed. At the same time, the dependence of the polarization conversion rate of the structure on the incident angle is studied. The results show that the structure has good polarization conversion performance in the incident angle range of 0-60°. Compared with previous designs, the polarization converter has not only simple structure, but also wide bandwidth. It has potential application value in polarization modulation of terahertz wave.