Based on the full vector wave equations, the dispersion formulas of vetorial modes were accurately established, and the expressions of field components were deduced in the hollow region,core region and cladding region. Then, the transverse electric field of the fundamental mode and the propagation constant were investigated. Based on the above analysis, the characteristics of mode were analyzed in detail by changing the main parameters of HOF, such as, the relationship between nneff and wavelength, radius of air hole, thickness of core. The raw of mode characteristics based on the varying number of cladding provides a basis for further research and application of hollow fiber.