The transfer matrix of the slab waveguide made up of a negative-refractive-index material is solved using the rigorous electromagnetic wave theory. The characters and application of the transfer matrix were also discussed. The dispersion relations of the three-layer symmetric slab waveguide possessing a negative-refractive-index guiding layer and positive-refractive-index surrounding medium are investigated by the transfer matrix method. The exotic properties of guided transverse electric(TE) waves in a left-handed waveguide were investigated graphically. There are no fundamental modes in a left-handed waveguide. The lowest mode was the first-order mode which had cutoff frequency. The first-order mode exits only when the parameters of the left-handed waveguide satisfied certain terms. Guided modes existed both for imaginary transverse wave numbers and real transverse wave numbers in a left-handed waveguide,while guided modes only exist only for real transverse wave numbers in a right-handed waveguide.