Aimed at the application of smoothing of multi-color spectral dispersion in inertial confinement fusion facilities, an independent design and optimization method for main unit components, including electro-optic modulators, dispersion gratings and continuous phase plates (CPP) and so forth, is proposed. The effects of parameters of electro-optic phase modulators, dispersion gratings and the CPP on the laser-quad irradiation characteristics are simulated and analyzed. The parameters of optimized smoothing of multi-color spectral dispersion are proposed, and the effect of the smoothing parameters on the characteristics of longitudinal filaments of lasers is simulated. Results indicate that the irradiation uniformity on the target surface can be further improved when we optimize the parameters of electro-optical modulator and dispersion grating of different sub-beams. When different CPPs are implemented for different sub-beams in the laser-quad, the focal-spot uniformity can be improved effectively and the proportion of hot spots can be decreased significantly. Moreover, the beam quality of the laser beam is analyzed by the power spectral density. The simulation results show that the smoothing of multi-color spectral dispersion can effectively decrease the peak intensity and make the light intensity distribution more uniform, which is benefit to suppress filaments of laser beams.