摘要： We theoretically propose a narrowband perfect absorber metasurface (PAMS) based on a silver surface phonon polaritons in the terahertz range. The PAMS has biarc on the top, a thin polar-dielectric in the middle and a silver layer at the bottom. The phonon polaritons have excited at the interface between the silver biarc and the polar dielectric and have enhanced the absorption of the PAMS. The absorption peak is at 36.813μm and the full width half maximum (FWHM) near 36nm and is independent of the polarization and incidence angle. The electric fields are located at the split of the biarc silver layer and the quality factor (Q) is 1150. The FWHM decreases with the decreasing of split width. When the thickness of bottom layer larger than 50nm, the narrow band and high absorption are insensitive of the thickness of those layer. The designed absorber may have useful applications in terahertz spectrum such as energy harvesting, thermal emitter, and sensing.