Abstract: The hybrid model for analyzing the helix tape considering its radial thickness is developed in this paper. In the hybrid model, by expanding the surface currents on the helix tape in a series of Chebyshev polynomials, simulating the helical thickness with vacuum layer and equaling the rods with multiple azimuthally symmetric layers, the dispersion equation and interaction impedance of helical slow wave structure with arbitrary tape width, supported by a radially stratified dielectric layer and enclosed by a metallic shell are obtained. The calculating results using hybrid model presented in the paper show good agreement with the experiment results.