Abstract: Polymeric Mach-Zehnder rib waveguide is an important component in polymeric integrated electro-optic devices. A new technique is used for computing the optical field distribution of the fundamental and higher order modes for TE modes of a polymeric Mach-Zehnder rib waveguide. The technique is based on the combination of the effective index method and the variational method，and has advantages such as high precision, low calculation complexity and high efficiency, which can provide theoretical reference and optimization method for the fabrication of polymeric electro-optic devices. Important parameters of the waveguide are discussed and their relations with the optical power propagation and loss characteristics are investigated by using the finite difference beam propagation method. The opt