Currently, power delivery fiber is limited by core diameter and material defects, and the conflict between large mode area and outstanding transmission performance in the mid-infrared wavelength range is difficult to solve. In this paper, a seven-tube hollow core anti-resonant fiber is proposed, in which the cladding tube is connected to the outsourcing layer in an intersecting manner. The fiber is numerically analyzed by the finite element method with perfectly matched layer boundary conditions, and the optimal results are obtained by comprehensively analyzing fiber loss and single-mode property. When the core diameter is 120.0 μm, the cladding tube thickness is 0.7 μm, the number of cladding tubes is 7, the cladding tube diameter is 84.0 μm and the outsourcing layer radius is 146.9 μm, the fiber loss is 0.004 dB/m at 3.0 μm, and for wavelength range from 2.5 to 3.6 μm, the fiber has a loss below 0.01 dB/m, a mode area over 6000 μm2 and excellent single-mode property. The proposed hollow core anti-resonant fiber can achieve low-loss single-mode transmission under large mode area conditions, which has great potential in the field of mid-infrared power delivery.