The interference signal of white-light interferometer with several broadband light sources is the superposition of those only with one broadband light source. Then the signal intensity is redistributed. An optimum wavelength combination that makes the intensity difference between zero-order and first-order fringe increase is found by theoretical analysis and computer simulations. The use of the optimum wavelength combination results in the more accurate determination of zero-order fringe, the enhancement of the system resolution, and the decrease of the needed signal-noise-ratio for identifying zero-order fringe. The method to select the optimum wavelength combination is also presented.