Polarization beam splitter (PBS) is a very important optical component in the fields of optical sensing and integrated optics. Terahertz wave is considered as the carrier of large capacity wireless communication in the future. And the structure design of dual hollow-core anti-resonant fiber is more variable, there is no strict requirement for cladding structure, and it can achieve higher performance to meet the needs of people's more diversity. Therefore, the design of PBS based on dual hollow-core anti-resonant fiber for terahertz band is more and more worthy of in-depth study. A dual hollow-core anti-resonance fiber based on cycloalkene polymer is proposed, further analysis and adjustment are carried out by changing the structural parameters of the optical fiber, on this basis, the PBS is designed and optimized. The structural parameters are as follows, the thickness of the inner cladding tube is 90 μm, the outer radius of the inner cladding tube is 335 μm, the inner radius of the outer tube is 2 000 μm, and the outer radius of the outer tube is 2 500 μm. And a PBS with the length of 119 cm, the ER of -24.831 3 dB and the bandwidth of about 2.2 μm is obtained.