Terahertz communication has the advantages of both microwave communication and optical communication, which is one of the most effective technical means to solve the problem of communication capacity shortage. In order to solve the problems of serious absorption loss and poor external disturbance resistance in terahertz band, a new terahertz fiber based on circular Photonic Crystal Fiber(PCF) structure is designed to support high performance Orbital Angular Momentum(OAM) modes transmission. The existing common materials are used as the fiber base material, and the high absorption loss of materials is offset by the innovation of hollow porosity arrangement in the fiber structure. The optimal parameters are selected to realize the stable transmission of six OAM mode groups with high mode quality, low confinement loss and wide bandwidth. The mode purity is above 88.9% and the confinement loss is below 10-7 dB/m in the 0.2~0.9 THz band. Through simulation, the key problem of combining terahertz and OAM technology is solved, which lays a theoretical foundation for the application of Mode Division Multiplexing(MDM) technology in terahertz communication system.参考文献原文> LI Shuhui, WANG Jian. Multi-orbital-angular-momentum multi-ring fiber for high-density space-division multiplexing[J]. IEEE Photonics Journal, 2013,5(5):7101007.