With the advancement of modern fiber-optic communication technology, the need for low-loss single-mode transmission optical fibers that can support high-speed optical communication with larger bandwidth and minimal transmission loss has become pressing. This study proposes a novel hollow-core anti-resonant fiber structure based on a single-ring nested design, which incorporates a small nested circle into the conventional single-ring five-tube double-nested structure. The transmission characteristics of the optical fiber are numerically simulated using the finite element method combined with perfectly matched layer boundary conditions. The numerical results show that in the range of 1400?1580 nm, the fiber achieves a higher-order mode suppression ratio exceeding 100, a confinement loss of less than 9.700×10^-5 dB/m, and a bending loss of less than 1.165×10^-2 dB/m at a bending radius of 5 cm. Furthermore, the dispersion is in the range of 1.020?1.222 ps/(nm·km). This hollow-core anti-resonant fiber satisfies the requirements for single-mode operation while achieving broadband low transmission loss, making it a promising candidate for applications in dense wavelength division multiplexing systems.