Abstract: The axial stiffness of metal hose is an important parameter in aerospace pipeline design, while there is a lack of fast and accurate engineering calculation method for its axial stiffness. In this study, the axial stiffness of wire braid and metal hose is theoretically analyzed, and a method for metal hose axial stiffness calculation is established. Firstly, a single wire in wire braid is simplified to a helical beam model. The geometrical description and coordinate transformation of the helical beam in different coordinate systems are derived by using a differential geometry method. The virtual work equations of the helical beam are derived, and the axial stiffness of the helical beam under fixed boundary and cyclic boundary is further obtained upon the virtual work principle. The influences of axial length, helix angle and helix diameter on axial stiffness are analyzed. The influences of different boundary conditions on the axial stiffness are analyzed, and the approximate equivalence of a fixed boundary and of a cyclic boundary is further found when the axial length of the helical beam is comparable to the wave length of the bellows (10 mm in this paper). A sub-wire-braid stiffness analysis method based on contact relationship is proposed to reflect the boundary nonlinear factors, thereby a calculation method of metal axial stiffness is finally established by combining the theory of helical beam stiffness and displacement. The consistency between the metal hose force-displacement curves obtained by calculation method proposed and the experimental results is verified in the range of small deformation. A methodology is provided for the design and the mechanical analysis of subsequent aerospace pipeline systems with metal hoses.