To achieve stable transmission of laser with lower loss, single mode, and single polarization in the mid-infrared band, This paper designs a bend-resistant hollow-core anti-resonant fiber configuration with a double-cladding nested structure. The finite element method is used to optimize the structural parameters, and the transmission characteristics of broadband low-loss single polarization of the fiber are verified through simulation. The confinement loss of this fiber is less than 0.01 dB/km within the wavelength range of 2.9-3.3 μm, and the high-order mode extinction ratio exceeds 1000, and the confinement loss is as low as 0.0014 dB/km at 3 μm wavelength. The symmetry of the fiber structure is destroyed by using different nested tube thicknesses, and the single-polarization characteristic of the fiber is theoretically investigated. Within the wavelength range of 2.996-3.004 μm, the polarization extinction ratio exceeds 10000, demonstrating an extremely stable single polarization effect. In addition, theoretical analysis indicates that this fiber also has excellent bending resistance performance. When the bending radius in the y-direction is greater than 5 cm, it can still ensure single-polarization laser transmission, and the bending loss is less than 3.11 dB/km. The designed hollow-core anti-resonant fiber configuration has great potential for application in mid-infrared fiber laser and other fields.