The convenient analytical method for the all-metal-cladding rib waveguide is presented.The metal-cladding rib waveguide is converted into the two-dimension slab one by using the effective refractive method, then the equation of satisfying effective refractive index and the formula of absorption loss coefficient are derived by the derivation method for the all- metalcladding rib waveguide. Taking this method as an example, optical propagation constant and the loss characteristics for SiO2 have been calculated actually. Some available results are obtained.