Based on the vector scattering theory and with bidirectional reflection distribution function and total scattering loss as evaluation indexes, the influence of interface electric field intensity on light scattering characteristics of multilayer highly reflective thin films is analyzed and theoretically and experimentally verified. The reflectivity at the center wavelength of 632.8 nm is required to be larger than 99%. Two kinds of multilayer dielectric high-reflectivity films are designed by using Ta₂O₅ and SiO₂ films on the premise of meeting the spectral design requirements. The surface reflectivity and the distribution of electric field intensity in the film system are analyzed, and a film system with an optimized interface electric field intensity is proposed. Finally, the effectiveness of the proposed method for reducing scattering caused by interface roughness of multilayer dielectric films by adjusting the interface electric field intensity of multilayer dielectric films is verified from the theoretical calculation and experiments.